Keep in mind that this setup is a one-time cost. Also, a lot of the code is related to configuring it the way the author wants it (via Home Manager).

Generally speaking, once you have a working NixOS config, incremental changes become extremely trivial, safe, and easy to rollback.

To provide another data point: I too use NixOS and oh boy that one-time is really costly. And while we're sharing Nix stuff for LLMs there's this piece of kit too: https://github.com/YPares/rigup.nix