Yes and no (mostly yes). Ideally, you have /nix/ where everything gets installed, then folders with symlinks in your homedir (one that builds your workspaces and another that versions them) with an environment variable in your bash_rc to hook you in.

You can put that /nix folder anywhere, but you can no longer use their binary package caches and it will recompile everything. This is because they hard-code paths for dependencies during build time.