Home Manager can be used in three primary ways:
Using the standalone home-manager tool. For platforms other than NixOS and Darwin, this is the only available choice. It is also recommended for people on NixOS or Darwin that want to manage their home directory independent of the system as a whole. See Section 1.1, “Standalone installation” for instructions on how to perform this installation.
As a module within a NixOS system configuration. This allows the user profiles to be built together with the system when running nixos-rebuild. See Section 1.2, “NixOS module” for a description of this setup.