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How do I make a macOS app out of my Python program?

I've made this question because I had to go through the whole process of creating my own application using Apple's somewhat lacking documentation, and without the use of py2app. I wanted to create the whole application structure so I know exactly what was inside, as well as create an installer for it. The latter of these is still a mystery, so any additional answers with information on making a custom installer would be appreciated. As far as the actual "bundle" structure goes, however, I think I've managed to get the basics down. See the answer below.

Edit: A tutorial has been linked at the end of this answer on using PyInstaller; I don't know how much it helps as I haven't used it yet, but I have yet to figure out how to make a standalone Python application without the use of a tool like this and it may just be what you're looking for if you wish to distribute your application without relying on users knowing how to navigate their Python installations.
A generic application is really just a directory with a .app extension. So, in order to build your application, just make the folder without the extension first. You can rename it later when you're finished putting it all together. Inside this main folder will be a Contents folder, which will hold everything your application needs. Finally, inside Contents, you will place a few things:
Info.plist
MacOS
Resources
Frameworks
Here you can find some information on how to write your Info.plist file. Basically, this is where you detail information about your application.
Inside the MacOS you want to place your main executable. I'm not sure that it matters how you write it; at first, I just had a shell script that called python3 ./../Resources/MyApp.py. I didn't think this was very neat though, so eventually I called the GUI from a Python script which became my executable (I used Tkinter to build my application's GUI, and I wrote several modules which I will get to later). So now, my executable was a Python script with a shebang pointing to the Python framework in my application's Frameworks folder, and this script just created an instance of my custom Tk() subclass and ran the mainloop. Both methods worked, though, so unless someone points out a reason to choose one method over the other, feel free to pick. The one thing that I believe is necessary, is that you name your executable the SAME as your application (before adding the .app). That, I believe, is the only way that MacOS knows to use that file as your application's executable. Here is a source that describes the bundle structure in more detail; it's not a necessary read unless you really want to get into it.
In order to make your executable run smoothly, you want to make sure you know where your Python installation is. If you're like me, the first thing you tried doing on your new Mac was open up Terminal and type in python3. If this is the case, this prompted you to install the Xcode Command Line tools, which include an installation of Python 3.8.2 (most recent on Xcode 12). Then, this Python installation would be located at /usr/bin/python3, although it's actually using the Python framework located at
/Applications/Xcode.app/Developer/Library/Frameworks/Python3.framework/Versions/3.8/bin/python3
I believe, but am NOT CERTAIN, that you could simply make a copy of this framework and add it to your Frameworks folder in order to make the app portable. Make a copy of the Python3.framework folder, and add it to your app's Frameworks folder. A quick side note to be wary of; Xcode comes packaged with a lot of useful tools. In my current progress, the tool I am most hurting for is the Fortran compiler (that I believe comes as a part of GCC), which comes with Xcode. I need this to build SciPy with pip install scipy. I'm sure this is not the only package that would require tools that Xcode provides, but SciPy is a pretty popular package and I am currently facing this limitation. I think by copying the Python framework you still lose some of the symlinks that point to Xcode tools, so any additional input on this would be great.
In any case, locate the Python framework that you use to develop your programs, and copy it into the Frameworks folder.
Finally, the Resources folder. Here, place any modules that you wrote for your Python app. You also want to put your application's icon file here. Just make sure you indicate the name of the icon file, with extension, in the Info.plist file. Also, make sure that your executable knows how to access any modules you place in here. You can achieve this with
import os
os.chdir('./../Resources')
import MyModules
Finally, make sure that any dependencies your application requires are located in the Python framework site-packages. These will be located in Frameworks/Python3.framework/Versions/3.X.Y/lib/python3.x.y/site-packages/. If you call this specific installation of Python from the command line, you can use path/to/application/python3 -m pip install package and it should place the packages in the correct folder.
P.S. As far as building the installer for this application, there are a few more steps needed before your application is readily downloaded. For instance, I believe you need to use the codesign tool in order to approve your application for MacOS Gatekeeper. This requires having a developer license and manipulating certificates, which I'm not familiar with. You can still distribute the app, but anyone who downloads it will have to bypass the security features manually and it will seem a bit sketchy. If you're ready to build the installer (.pkg) file, take a look at the docs for productbuild; I used it and it works, but I don't yet know how to create custom steps and descriptions in the installer.
Additional resources:
A somewhat more detailed guide to the anatomy of a macOS app
A guide I found, but didn't use, on using codesign to get your app past Gatekeeper
A RealPython tutorial I found on using PyInstaller to build Python-based applications for all platforms

Install a CMake macro script from within a python package install script (using setup.py)

So I have a Python package – it’s all set up on PyPI, and on GitHub, no problem. This is something I’m relatively familiar with.
What is unknown to me is: the notion of installing a CMake script as part of the python package install process. The python package in question is a development tool – you use it to preprocess some of your C/C++/Obj-C/Obj-C++ source files and generate some predefined macros in a header – and it works well when it’s wrapped in a CMake macro (for example like so) and executed as part of a proper chain of dependencies.
For one, I am not sure how to approach this, as there seem to be significant differences between the setuptools sandbox stance and distutils’ willing systems-level installer integration – and then even if I did know how to go about setting things up correctly in setup.py, I can’t find a good precedent on where a CMake script pertaining to a Python package might live.
All thoughts and insights on the matter are welcome.

It took me a while to understand your question. If I understand correctly, what you are trying to do is provide the IodSymbolize.cmake in the standard installation location of cmake so that other users/projects who rely on your software(symbolizer) can use it in their build process. I think you are thinking in a good direction, trying to provide services for end users of your package. Good question!
Here is my understanding of how things work in the cmake world.
Say I am an end user who wants to use "symbolizer" executable. What I would do is
find_package(symbolizer). This would try to figure out the location of the executable and it would set certain variables which can be used in the build process.
You need to provide Findsymbolizer.cmake file.
Please take a look at : http://www.cmake.org/Wiki/CMake:How_To_Find_Libraries
Also look at the Find*.cmake files provided in /usr//share/cmake/Modules directory if you are Unix/Linux platform.
Once the Findsymbolizer.cmake file is working properly, send it to the cmake mailing list for review. Once accepted it can be packaged in the next release of cmake. Then your module is usable with cmake. Hope I answered your question. Please update if you need more info.

Python4Delphi-powered program, how to deploy it?

My Delphi program uses Python4Delphi, and the Python script uses some standard libs. When deploying my program I don't want an entire Python installation, and it must work with python27.dll. What are the minimal set of necessary files? The document in Python4Delphi is dated and it's not clear to me...
Thanks for your help.

When I did this, I made the list myself, of what I needed for my embedded python application to work.
I remember this worked with python15.dll:
PythonXX.dll should work, without any other external files other than the Visual C++ Runtime DLLs, which require a side-by-side manifest (see the p4d wiki page) to work.
If you want to IMPORT something, then you need to ship it and anything it depends on. That means, either you pick part of the python standard libraries you want, or you pick all of it. There is no way you need all of Python's standard libraries. But I wouldn't want to live without OS and a a few other key ones. BUt the decision is yours.

Installing a Python program on Linux

I wrote a Python program. I would like to add to it an installation script that will set up everything necessary - like desktop icon, entry in the menu, home directory file, etc.
I'm working on Linux (ubuntu). When a Python program is installed, what needs to happen in general? I know that it probably depends on the nature of the program.
Can you give me some general ideas? Or, point me in the right direction? I have no idea how to look for this on Google.
Thanks

If it's a Python program you're trying to package, you should consider using its 'standard' distribution framework distutils. I can't replicate the entire document here but I'd recommend that you read it. Once you're done with that, check out the Hitchhikers guide to packaging which contains details on distribute - the extensions to distutils that allow you to package and distribute more effectively.

You could create an rpm easily using checkinstall. Search for checkinstall in google and download it. It will allow you to create an rpm and set the options.

For Ubuntu if you want it to be easily distributable to other Ubuntu users it'll have to be packaged properly, which is no simple task. You might want to consult their Packaging Guide for more information.
Otherwise, generally speaking there are a few standard packaging options for Python. Setuptools is popular, but becoming reviled lately. Read James Bennett's blog post "On Packaging" for a decent in-depth look into the ups and downs of the Python packaging world.

How a program is launched and placed in the menu is determined by a .desktop file (you can read the specification or just look at some examples from /usr/share/applications). Properly installing a program (placing all files in the right directories and so on) requires either making a package like a deb or rpm, or you could use something like distutils or setuptools.
It may also help to just look at some (open source) examples of Python programs for Linux.

Py2App Can't find standard modules

I've created an app using py2app, which works fine, but if I zip/unzip it, the newly unzipped version can't access standard python modules like traceback, or os. The manpage for zip claims that it preserves resource forks, and I've seen other applications packaged this way (I need to be able to put this in a .zip file). How do I fix this?

This is caused by building a semi-standalone version that contains symlinks to the natively installed files and as you say, the links are lost when zipping/unzipping unless the "-y" option is used.
An alternate solution is to build for standalone instead, which puts (public domain) files inside the application and so survives zipping/unzipping etc. better. It also means the app is more resilient to changes in the underlying OS. The downside is that it is bigger, of course, and is more complicated to get it set up.
To build a stand alone version, you need to install the python.org version which can be repackaged.
An explanation of how to do this is here, but read the comments as there have been some changes since the blog post was written.

use zip -y ... to create the file whilst preserving symlinks.

You probably need to give it your full PYTHONPATH.
Depends on your os. Here's how to find out:
import os [or any other std module]
os.file()