I keep seeing this from people online but I have yet to see Nix in the wild at any large organization. For such a "game-changing" thing, it certainly doesn't have the meat space following you see online.
To me, I tried Nix, got frustrated with packages, realized I'm just using someone else's abstractions for defining configuration files (with the same kind of quality you'd find on Ansible galaxy), and realized it's not solving a problem I have.