What’s powerful about nix is the language IMO. I was able to build an automatic WireGuard setup[1] with tagging that automatically works on each new machine thanks to the ability to do config as code. Just provide some basic config for each machine and the code turns it into an interface with peers.
The issue to me isn’t the language persay (it’s really a tiny surface area language, see the built in/lib functions [2]) but the tooling built around packaging is a hodgepodge mess of semi-documented workarounds (with Nixpkgs blessed ways vs user libraries) and is extremely difficult to approach and understand.
[1]: https://github.com/jordanisaacs/dotfiles
[2]: https://teu5us.github.io/nix-lib.html