This is something that I struggle with. I know how to find top-level packages like git or cowsay. But what about utilities under nested paths? I always spend ages digging through the nixpkgs source code to try to find utilities to use in my nix expressions.
Today I want to use buildRustPackage. It’s defined here, and is propagated here. But how do I access it given a pkgs variable? I have no idea!
https://search.nixos.org/packages is no help
nix search nixpkgs doesn’t find it
I think I need to search by attribute name, not by derivation name. But I don’t know how to do that.

There was a talk about that problem at this years NixCon, maybe it’ll give you some ideas.
https://media.ccc.de/v/nixcon-2023-36333-finding-things-in-nixpkgs-and-nixos-source
Oh very nice - thanks!