Nix / NixOS

I have no idea how you're getting packages older than Debian. Unstable is a rolling release and stable has a 6 month release cadence with no LTS. Were you pulling from an old dead repo? If you followed an outdated guide, they probably linked you to an old one.

I do agree that the learning curve is steep and the knowledge is nontransferrable though. In my case, that just encouraged me to unify all my systems onto NixOS at home. Not sure if that's a solution or addiction yet.