maybe

systems/x86_64-linux/steamdeck/jovian.nix

@@ -26,4 +26,29 @@
 
     hardware.has.amd.gpu = true;
   };
+
+  specialisation."vanilla".configuration = {
+    services.desktopManager.gdm.enable = true;
+    jovian = {
+      steam = {
+        enable = true;
+        autoStart = false;
+        user = "deck";
+        desktopSession = "gnome";
+      };
+
+      steamos = {
+        useSteamOSConfig = true;
+      };
+
+      devices = {
+        steamdeck = {
+          enable = true;
+          enableGyroDsuService = true; # If enabled, motion data from the gyroscope can be used in Cemu with Cemuhoo
+        };
+      };
+
+      hardware.has.amd.gpu = true;
+    };
+  };
 }