refactor: make the whole thing more generic

modules/nixos/hardware/gbmonctl.nix

@@ -0,0 +1,23 @@
+{ pkgs, lib, config, ... }:
+with lib;
+
+let cfg = config.hardware.gbmonctl;
+
+in {
+  options.hardware.gbmonctl = {
+    enable = mkOption {
+      type = types.bool;
+      default = false;
+      description = mkDoc ''
+        Enables a CLI tool to change monitor settings over USB to the Gigabyte M32U
+
+        In theory any Gigabyte Monitor that uses a Realtek HID device (presumably the M28U also uses this) to control it over OSD sidekick should have the same protocol, but this is the only one I own.
+      '';
+    };
+  };
+
+  config = mkIf cfg.enable {
+    environment.systemPackages = [ pkgs.gbmonctl ];
+    services.udev.packages = [ pkgs.gbmonctl ];
+  };
+}