sway: allow setting both internal and external monitors

system/greetd.nix

@@ -25,6 +25,9 @@ in
     # Enable the X11 windowing system.
     services.xserver.enable = false;
 
+    # Enable external monitor configuration (brightness)
+    hardware.i2c.enable = true;
+
     # enable sway window manager
     programs.sway = {
       enable = true;