I'm not big on programming languages being used for configuration. It adds a lot of complexity and maintenance burden. Configurations are often read and your reader isn't a compiler but now they have to imagine what the final configuration state will be after evaluating the "program" that generates the configuration. I think plain old configuration languages are better, even if verbose, since the usual text-based tooling works quite well for managing, searching, etc.

I use nix a lot and the main thing that bothers me about it is the language. People are quick to get clever with it. It becomes a morass of code that is difficult to read for anyone but experts and when it breaks and your not that expert... good luck fixing it.