A lot of problem with Python packages is the fact that a lot of Python programs is not just Python. You have a significant amount of C++, Cython, and binaries (like Intel MKL) when it comes to scientific Python and machine learning. All of these tools have different build processes than pip so if you want to ship with them you end up bring the whole barn with you. A lot of these problems was fixed with python wheels, where they pack the binary in the package.

Personally, I haven't ran into a problem with Python packaging recently. I was running https://github.com/zyddnys/manga-image-translator (very cool project btw) and I didn't ran into any issues getting it to work locally on a Windows machine with Nvidia GPU.