I share your concern about over dependence, but for different reasons.

There's a lot of metadata Github has that's not backed up in the git repo. For example. pull requests, issues, projects, milestones, wikis etc.

There appears to be third party tools that can back this metadata up using Githubs API. I wonder if anyone bothered. Kinda doubt it.

After the Google cloud UniSuper incident, I think it's clear that no org is immune from accidentally deleting everything.

which somehow belong to Microsoft and is not good for privacy.

It's hard for me to guess exactly what your concern is. There's nothing stopping you from using an anonymous account on Github to contribute. Or just connecting to it via Tor / VPN.

If its mostly about sticking to principles, then you might like https://guix.gnu.org/ more.

There's also these are projects you could contribute to:

• https://tvl.fyi/ Tvix rewrite of cppnix in rust
• https://lix.systems/ recent cppnix fork
• auxolotl.org An alternative to the Nix ecosystem (in the works)

I think they're all using forgejo or some FOSS git forge. At least I think aux is still planning moving to forgejo. However, I'm not aware of anyone still planning to fork nixpkgs.

• previous nixpkgs mirror discussion: https://discourse.nixos.org/t/what-would-a-nixpkgs-mirror-look-like/16293