That said, I'm sure Python, Go, Rust and other languages will be supported very soon.
There's no technical or political obstacle here.
https://pip.pypa.io/en/stable/reference/pip_wheel/#find-link...
You can also link directly to a package with `--find-links` if you specify an egg fragment, e.g. 'https://github.com/project/reponame/tarball/version#egg=pack.... (The version must match that in setup.py.)
Keep in mind it's in beta.
So, it's not really all that surprising of an initial set of choices for them to make.
There only other that I heard is anaconda, but that's made by 3rd party (not affiliated fir PSF), it is not just Python but also R since it targets scientific community. I also believe it is primarily used by windows users. It is packaging for scientific tools that happen to also have python.
Edit: from another comment I see that underneath anaconda apparently uses PyPI for python packages (I didn't know, since I never used it) so it is not even a proper repo, just an abstraction to PyPI (and possibly whatever R is using)
Not saying Python doesn't have enterprise value, but we have to consider that this is an MVP, so it makes sense for them to limit to a subset of languages they feel comfortable about.
Installing directly from github is possible, but it works ok for a one off, if you have a package with your own dependencies then that doesn't scale.
It also covers source installations it doesn't work well for compiled.