It does, if your extensions are provided as wheels. In which case the resulting pyz file will be runnable on any machine using the OS those wheels are compiled for.

Let's try an example with numpy:

    $ py -m venv foo
    $ foo\Scripts\activate
    $ pip install numpy
    $ code hello_numpy.py
    # import numpy as np
    # def main():
    #     print(np.arange(15).reshape(3, 5))
    $ python hello_numpy.py
    [[ 0  1  2  3  4]
    [ 5  6  7  8  9]
    [10 11 12 13 14]]

Now with shiv:

    $ copy hello_numpy.py foo\Lib\site-packages
    $ shiv -e hello_numpy.main --site-packages test\Lib\site-packages\ -o hello_numpy.pyz
    $ python hello_numpy.pyz
    [[ 0  1  2  3  4]
    [ 5  6  7  8  9]
    [10 11 12 13 14]]

So it works fine, but remember:

- it will only run on the system this particular numpy wheel has been designed to run on. In my case cp38-win_amd64.

- it will comes bundle with numpy. Numpy is quite big, which means your hello world pyz will be 14.1 Mo.

- it needs to unzip, so the first run will be slow