If you need something that exists outside the repository it can get complicated. Even playing within the repository can have pitfalls at least on Guix which is

If you need something that exists outside the repository it can get complicated. Even playing within the repository can have pitfalls at least on Guix which is what I've mainly used (like having a package appear in two profiles can cause issues that are non-obvious or like using "guix shell gcc binutils" instead of " guix shell gcc-toolchain"). Some of that has to do with the fact of what an expected *nix install is supposed to be and expectations of what should be installed on a users system and so are not marked as dependencies or requirements when they really are. I am curious about how a system designed from the ground up with this in mind might be better.