I ffing give up for today...

modules/nixos/application/steam/default.nix

@@ -0,0 +1,55 @@
+{ inputs, config, lib, pkgs, namespace, ... }:
+let
+  inherit (lib) mkIf mkEnableOption;
+
+  cfg = config.${namespace}.application.steam;
+in
+{
+  options.${namespace}.application.steam = {
+    enable = mkEnableOption "enable steam";
+  };
+
+  config = mkIf cfg.enable {
+    # home.packages = with pkgs; [ protonup ];
+
+    # home.sessionVariables = {
+    #   STEAM_EXTRA_COMPAT_TOOLS_PATHS = "\${HOME}/.steam/root/compatibilitytools.d";
+    # };
+
+    programs = {
+      steam = {
+        enable = true;
+        package = pkgs.steam-small.override {
+          extraEnv = {
+            DXVK_HUD = "compiler";
+            MANGOHUD = true;
+          };
+        };
+
+        gamescopeSession = {
+          enable = true;
+          args = ["--immediate-flips"];
+        };
+      };
+
+      # https://github.com/FeralInteractive/gamemode
+      gamemode = {
+        enable = true;
+        enableRenice = true;
+        settings = {};
+      };
+
+      # gamescope = {
+      #   enable = true;
+      #   capSysNice = true;
+      #   env = {
+      #     DXVK_HDR = "1";
+      #     ENABLE_GAMESCOPE_WSI = "1";
+      #     WINE_FULLSCREEN_FSR = "1";
+      #     WLR_RENDERER = "vulkan";
+      #   };
+      #   args = ["--hdr-enabled"];
+      # };
+    };
+  };
+}