woot, got it building, on to the next step

modules/home/desktop/applications/steam.nix

@@ -1,14 +1,12 @@
-{ options, config, lib, pkgs, user, ... }:
+{ config, lib, pkgs, user, ... }:
 let
-  inherit (lib.modules) mkIf mkForce mkMerge;
+  inherit (lib) mkEnableOption mkIf mkForce mkMerge;
 
   cfg = config.modules.${user}.desktop.applications.steam;
   desktop = config.modules.${user}.desktop;
 in
 {
-  options.modules.${user}.desktop.applications.steam = let
-    inherit (lib.options) mkEnableOption;
-  in {
+  options.modules.${user}.desktop.applications.steam = {
     enable = mkEnableOption "Enable steam, the game/software store";
     hardware.enable = mkEnableOption "Support for steam hardware";
   };

modules/home/desktop/default.nix

@@ -1,17 +1,10 @@
-{ config, options, lib, pkgs, user, ... }:
+{ lib, user, ... }:
 let
-  inherit (builtins) isAttrs;
-  inherit (lib.attrsets) attrValues;
-  inherit (lib.modules) mkIf mkMerge;
-  inherit (lib.my) anyAttrs countAttrs value;
-
-  cfg = config.modules.${user}.desktop;
+  inherit (lib.types) either str;
+  inherit (lib.my) mkOpt;
 in
 {
-  options.modules.${user}.desktop = let
-    inherit (lib.types) either str;
-    inherit (lib.my) mkOpt;
-  in {
+  options.modules.${user}.desktop = {
     type = mkOpt (either str null) "wayland";
   };
 }

modules/home/themes/default.nix

@@ -1,6 +1,6 @@
 { config, lib, pkgs, user, ... }:
 let
-  inherit (lib) mkIf;
+  inherit (lib) mkIf mkDefault;
   inherit (lib.options) mkOption mkEnableOption;
   inherit (lib.types) nullOr enum;
 
@@ -31,7 +31,7 @@ in {
       base16Scheme = "${pkgs.base16-schemes}/share/themes/${cfg.theme}.yaml";
       image = ./${cfg.theme}.jpg;
       polarity = cfg.polarity;
-      targets.qt.platform = "kde6";
+      targets.qt.platform = mkDefault "kde6";
     };
   };
 }

modules/system/desktop/gaming.nix

@@ -11,10 +11,15 @@ in
   };
 
   config = mkIf cfg.enable {
-    jovian.steam = {
-      enable = true;
-      autoStart = true;
-
+    jovian = {
+      steam = {
+        enable = true;
+        autoStart = true;
+        user = "chris";
+        updater.splash = "steamos";
+        desktopSession = "gamescope-wayland";
+      };
+      steamos.useSteamOSConfig = true;
     };
   };
 }