I find I have a lot of trouble with updating with nixos. I really like the OS but I find that when I have something like Claude Code and I need to update to the newest version, I just have trouble. It just seems like a lot of work updating versions otherwise NixOS is really awesome and great.
The kind of problem you're describing is what Nix handles exceptionally well. Don't install everything at the system level (NixOS). Home Manager is better suited for things like Claude. And even if you did choose to install Claude from your NixOS configuration, you can draw from a different Nixpkgs commit. Usually, using the latest stable channel for NixOS and nixpkgs-unstable for the rest is good enough.
I converted my homelab with an Nvidia graphic