personally, the way I do it is: /etc/nixos/roles/foo/default.nix has config for the 'foo' role (eg, I have a desktop role that enables all my GUI options) con

personally, the way I do it is: /etc/nixos/roles/foo/default.nix has config for the 'foo' role (eg, I have a desktop role that enables all my GUI options) configuration.nix and hardware-configuration.nix in /etc/nixos/ are symlinked to the actual files in /etc/nixos/hosts/<hostname>/ in the imports section of each machine's configuration.nix, I import /etc/nixos/roles/foo for each role the machine should use. for your graphics card example, I have 'nvidia' and 'nvidia470' roles that pull in their respective nvidia driver (due to an old gaming laptop that requires the legacy driver version) I have a 'core' role that all machines import, with the global config I want on every host this allows me to version-control my entire /etc/nixos directory (managed as a private git repo, replicated using syncthing rather than pushed to Github/Gitlab/etc). the symlinks in /etc/nixos are in .gitignore because they're machine-specific, and the actual per-host config files are able to be tracked in their own directories.