I would naively expect that if you run garbage collection on a regular basis that it should take no more space. Is that not true, or is running it on a regular basis the sticking bit?
I suppose you could, but Nix (and NixOS) defaults to keeping packages for an insane amount of time. 3 months of regular Nix use can accrue ~300gb of packages, which is definitely not what you'd have on something like Homebrew.
