I would like to see a Odoo package too for NixOS. Unfortunately I’m a beginner with Nix, so I can’t help a lot. Nevertheless, I did take the opportunity to start learning and could finally install Odoo 14, but then something did break my installation and I gave up. If you like to check: -nixpkgs-odoo
As far as I can see from the other links they don’t provide the necessary tooling and get a full dev environment yet.