use only stable nix. override nixpkgs for inputs you add. after first build, use offline and no-substitute flags on reuse, alias such command. use nixdirenv. r

use only stable nix. override nixpkgs for inputs you add. after first build, use offline and no-substitute flags on reuse, alias such command. use nixdirenv. read and setup store/gc settings work for you. do not use nixenv nor nix profile.