It is possible to use from a completely unprivileged environment by putting the nix store in your home directory instead of `/nix`. But (and it's a big but) you

It is possible to use from a completely unprivileged environment by putting the nix store in your home directory instead of `/nix`. But (and it's a big but) you'll then have to build all packages from scratch because the hashes for you packages will be different to the ones in the nix binary cache.