Inspect a NixOS configuration. More information: https://nixos.org/manual/nixos/stable/index.html#sec-modularity.
nixos-option option_key
nixos-option boot.kernelModules
nixos-option users.users.username.openssh.authorizedKeys.keyFiles|keys
nixos-option nix.buildMachines
NIXOS_CONFIG=path_to_configuration.nix nixos-option option_key
nixos-option -r users.users.user