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Are these pip commands equivalent when installing packages from a local directory?

I have a situation where I need to download some Python packages on an internet-connected asset, then install them on a disconnected asset. Let's say I go through the following steps:
Create a requirements file, requirements.txt
Download packages to a local folder: py -m pip download -r "requirements.txt" -d "pkg_dir"
Move requirements.txt and pkg_dir to the disconnected asset
Install the packages from pkg_dir: here is my question
Is this command: py -m pip install -r "requirements.txt" --no-index --find-links "pkg_dir"
equivalent to this command: py -m pip install -r "requirements.txt" --index-url "pkg_dir"
The pip documentation states that the --index-url is the
Base URL of the Python Package Index (default https://pypi.org/simple). This should point to a repository compliant with PEP 503 (the simple repository API) or a local directory laid out in the same format.
(emphasis mine)
I'm just curious if these commands behave the same way when the "index URL" is a local folder. I know that the typical --no-index --find-links variant works as expected; this is just something I was wondering about.

install python package at current directory

I am mac user, used to run pip install with --user, but recently after brew update, I found there are some strange things, maybe related.
Whatever I tries, the packages are always installed to ~/Library/Python/2.7/lib/python/site-packages
Here are the commands I run.
$ python -m site --user-site
~/Library/Python/2.7/lib/python/site-packages
$ pip install --user -r requirements.txt
$ PYTHONUSERBASE=. pip install --user -r requirements.txt
So what should be the problem?
I used for lambda zip packaging
Updates:
If using Mac OS X and you have Python installed using Homebrew (see Homebrew), the accepted command will not work. A simple workaround is to add a setup.cfg file in your /path/to/project-dir with the following content.
[install]
prefix=
https://docs.aws.amazon.com/lambda/latest/dg/lambda-python-how-to-create-deployment-package.html

You can use the target (t) flag of pip install to specify a target location for installation.
In use:
pip install -r requirements.txt -t /path/to/directory
to the current directory:
pip install -r requirements.txt -t .

What does pip install . (dot) mean?

I have a shell script whose last line is:
pip install .
What does it do?
pip install <package-name> installs the specified package
pip install -r requirements.txt installs all packages specified in requirements.txt
But I am not sure what the above command does.

Explicitly, pip install . will execute the setup.py file in the current directory (which will usually load a requirements.txt file).

"Install the project found in the current directory".
This is just a specific case of pip install /path/to-source/tree.
To quote the the pip install documentation describing this usage:
pip install [options] [-e] <local project path> ...

What does " -r " do in pip install -r requirements.txt

I looked up how to install multiple packages from a requirements document using pip. The answers were mostly:
pip install -r requirements.txt
What does the -r do though? I can't find an answer for this and it isn't listed when I run pip help.

Instead of pip --help, look into pip install --help:
-r, --requirement Install from the given requirements
file. This option can be used multiple
times.
Also see these documentation paragraphs:
pip install
Requirements Files.

-r will search for requirement file.
pip install --help
will help you !!

May, 2022 Update:
If you run this command below without "-r":
pip install requirements.txt
You will get this error below:
ERROR: Could not find a version that satisfies the requirement requirements.txt (from versions: none)
HINT: You are attempting to install a package literally named "requirements.txt" (which cannot exist). Consider using the '-r' flag to install the packages listed in requirements.txt
ERROR: No matching distribution found for requirements.txt
Because "pip" tries to install the package "requirements.txt" instead of installing the packages listed in "requirements.txt". Of cource, the package "requirements.txt" doesn't exist in PyPI while for example, the packages "django" and "pillow" exist in PyPI:
pip install django
pip install pillow
So, to install the packages listed in "requirements.txt", you must need "-r";
pip install -r requirements.txt
You can check what "-r" means by running the command below:
pip install --help
-r, --requirement Install from the given requirements file. This option can be used multiple times.

In your case pip install -r requirements.txt will install the libraries listed in your requirements.txt file.

pip install requirements.txt
Above statement looks for a python package named requirements.txt. No such package exists. Your intention is that pip install opens the txt and reads the packages from there. The -r allows pip install to open requirements.txt and install the packages inside of it instead.

Alternative download options for `pip` sources.

I would like to install a set of packages from requirements.txt. pip seems to be incredibly slow in the default operation (1~5 kbps).
pip install -r requirements.txt
The following command was not much of help either; the download was still slow.
pip install --download DIR -r requirements.txt
The objective now is to download those package from the same link that pip would prefer, but download them with an accelerator (like axel achieving 500-700 kbps) to a directory DIR. Then I would be able to install them locally using the command.
pip install --no-index --find-links=DIR -r requirements.txt
How could I do this?
Specs: Pip-6.0.6, Python-2.7, Mac OS X 10.9
PS: All this to install Odoo (formerly OpenERP).