iirc, you can have a different base path, but you have to recompile every package locally to have the correct patched paths. I forget where I read about this.
Seems like an unavoidable consequence of how modern software is built
It's actually an unavoidable consequence of what makes Nix great. There is no loader that looks up libs in /lib, the paths are directly hardcoded into the binary. This is how Nix sidesteps versioning hell entirely.
It really isn't unavoidable on macOS. @rpath is designed specifically to handle this sort of thing, and is how all the command line tools distributed with Xcode link to libraries embedded in Xcode and continue working even when you drag Xcode to a new location.
Admittedly supporting that would require updating how all the tools are built and not just defaulting to Whatever Linux Does™, which is probably too much effort to justify in this case, but it is hardly an unsolvable (or even an unsolved) problem.
As far as I understand, you could pad the paths for the server farm builds then overwrite them on local machine install like Spack package manager does, so maybe not unavoidable?
Seems like an unavoidable consequence of how modern software is built