There's no reason why a package-management system needs to be language-specific; dependencies are often cross-language. Hell, even some blocks of code contain more than one language.
The package-management system is responsible for deploying packages. The way a package is deployed should depend on the operating environment, not on the language. These language-specific packaging arrangements typically deploy into some private part of the file-system, organized in its own idiosyncratic way.
Using git as a repository is just nuts. Git is privately-owned, and stuffed with all kinds of unaudited junk. You can't audit everything you install by hand; so these systems force you to install unaudited code, or simply not install.
I've been using Debian derivatives for years. I appreciate having an audited repository, and an installation system that deploys code to more-or-less predictable filesystem locations.