I think the initial migration towards nixOS is the hardest point, since it requires learning a bunch of new things all at once in order to get the system into a usable state that matches your expectations and preferences. The key benefit of using an LLM is that it makes it really easy to get your system into a useful initial state, and then you can safely learn and experiment incrementally with a mix of tools.
When I started off I didn't understand everything, but at this point I feel I have a very good understanding of everything in my configuration file.
Unless you're brand new to Linux or computing, it's not a mystery what a given nix config change is ever doing.
You can probably guess what this does:
networking.firewall.allowedTCPPorts = [ 8080, 9000 ];
I am not brand new - and I don't know what the heck the config is doing.
That is why I rely on documentation.
The "code is self-explanatory" is always an attempt to not have useful documentation and try to rationalise that problem away.
You can read documentation on an as-needed basis or to your heart's content.
The point is that the majority of the day to day changes I make to my desktop environment aren't so critical that I need to do more than read an AI agent's proposed changes to my config and accept them when they look reasonable.
And I don't think looking up the exact config options to NixOS' networking system does anything to increase my knowledge of the OS. It's just a triviality.