What? I compile my arm64 system on a amd64 system and send them to my cache server so my arm systems don’t have to do the work and just download the outputs and apply them.
That's something I would like to try for my PinePhone. It's been tedious to do development for it, as the PinePhone's CPU struggles with most compilation tasks. Using Nix would be a good way of building for that platform's somewhat exotic features (arm64 and musl libc) on a more powerful machine, without confusing the system package manager with package versions outside the distribution - I should be able to copy the Nix derivations over and install them temporarily with nix-shell. Thanks for the inspiration!
Make sure you use copy-closure and target the result directory. My fist attempts had some crazy find script copying all of nix-store with copy-closure. You can skip this part if you make the build machine the same as the cache machine as the results are automatically cached.