refactor: make the whole thing more generic

modules/nixos/hardware/fv43u.nix

@@ -0,0 +1,17 @@
+{ pkgs, lib, config, username, ... }:
+with lib;
+
+let cfg = config.hardware.fv43u;
+
+in {
+  options.hardware.fv43u = {
+    enable =
+      mkEnableOption "Enable optimisations for the Gigabyte FV43U monitor";
+  };
+
+  config = mkIf cfg.enable {
+    fonts.fontconfig.subpixel.rgba = "bgr";
+    hardware.gbmonctl.enable = true;
+    boot.kernelParams = [ "video=3840x2160@144" ];
+  };
+}