Seconded. NixOS's documentation has consistently been the worst I've read, always forcing me to go to the source code to try and understand what in the world is happening. It makes quick changes to new things nigh impossible. I had to resort to taking notes when I understood things about nix in order to retain the knowledge or at least link to where I could easily regain it.
The nixos wiki was marginally better and https://nixlang.wiki/ has been better. However the latter is less known so has less content. All in all, nix documentation is still bad.
Anti Commercial AI thingy
CC BY-NC-SA 4.0