Yes Nix is forked. There were some attempts to fork nixpkgs, but they failed because it's far too much work to maintain something like nixpkgs. Nix being forked is less of an issue, because at the very least everyone needs to be compatible with nixpkgs. I think it's ok to have multiple implementations, they lead to exploration of new directions (e.g. one of the projects attempts to reimplement Nix in Rust). Well and of course, Guix started as a fork.
I agree that the infighting is not nice. But to be honest, when you just use NixOS and submit PRs, you do not really notice them. It's not like people are fighting them in the actual PRs to nixpkgs.
Some of the more drawn-out arguments are in or about the RFCs repo, though, so it's not just chat platforms or forum where the fights break out. To your point the RFC repo is also something that not every would-be contributor would touch or need to.
I agree, but it makes me feel supremely uneasy to use something where the main team does Soviet-style purges where they mute/exile/ban community members not because they were being offensive but because they committed wrongthink. Even worse is that they're often prolific devs.
Ironically enough the closest comparison I could make is driving a Tesla. Even if the product is great, you're supporting an organisation that is the opposite.
I think the Nix team will continue to slowly chase away competent people until the rot makes the whole thing wither, at which point everyone switches their upstream over to Determinate Systems' their open core. Although I'm hoping DS will ultimately go the RHEL-Fedora route.
I agree that the infighting is not nice. But to be honest, when you just use NixOS and submit PRs, you do not really notice them. It's not like people are fighting them in the actual PRs to nixpkgs.