It should be pointed out that you can install the nix package manager in Arch (or whatever other Linux, or macOS, etc.), so you can try out nix's declarative package management without actually switching to NixOS.
I tried this on my previous laptop and ran into a number of issues once I tried to install anything with a GUI. It's fine for shells and CLI tools though. I migrated some configs over to a Nix configs under Arch, and while it was a pain to initially set up NixOS (unfamilarity), it's a lot easier doing everything else now.
Yeah, I’m not sure how up-to-date my knowledge is, but opengl and the like are exceptions to the usual deterministic handling of dependencies on non-NixOS distros (not because it is unable to do so, I think it is mainly to avoid storing everything n-times with nvidia/amd), and one has to specify them. It was quite a time I ran nix on a non-nixos distro but there is this tool https://github.com/guibou/nixGL that meant to solve the issue of graphical programs.
