users/guest: init and add steam

users/guest/common/optional/graphical/steam.nix

@@ -0,0 +1,30 @@
+{
+  pkgs,
+  ...
+}:
+{
+  home.packages = with pkgs; [
+    gamescope
+    steam
+  ];
+
+  systemd.user.services.steam-big-picture = {
+    Unit = {
+      Description = "Steam Big Picture in Gamescope";
+      After = [
+        "graphical.target"
+        "default.target"
+      ];
+    };
+    Service = {
+      ExecStart = ''
+        ${pkgs.gamescope}/bin/gamescope --rt --backend drm --steam -- \
+          ${pkgs.steam}/bin/steam -pipewire-dmabuf -tenfoot
+      '';
+      Restart = "always";
+    };
+    Install = {
+      WantedBy = [ "default.target" ];
+    };
+  };
+}

users/guest/default.nix

@@ -0,0 +1,66 @@
+{
+  config,
+  pkgs,
+  lib,
+  ...
+}:
+let
+  inherit (lib)
+    optional
+    ;
+  name = "guest";
+  hostFile = ./. + "/${config.networking.hostName}.nix";
+in
+{
+  users.users.${name} = {
+    description = "Guest";
+    extraGroups = [
+      "audio"
+      "input"
+      "render"
+      "video"
+    ];
+    group = "users";
+    isNormalUser = true;
+    shell = pkgs.zsh;
+  };
+
+  home-manager.users.${name} = {
+    imports = [
+      ./common/optional/graphical/steam.nix
+      {
+        home.persistence."/state" = {
+          directories = [
+            ".local/state/wireplumber"
+          ];
+        };
+        home.persistence."/persist" = {
+          directories = [
+            ".config/gamescope"
+            ".local/share/icons"
+            ".local/share/Steam"
+            ".local/share/vulkan"
+            ".steam"
+          ];
+        };
+      }
+    ]
+    ++ optional (builtins.pathExists hostFile) hostFile;
+
+    home = {
+      username = name;
+    };
+
+    xdg.enable = true;
+  };
+
+  services.getty = {
+    autologinOnce = true;
+    autologinUser = "guest";
+  };
+
+  # Workaround: https://github.com/nix-community/home-manager/issues/7166
+  systemd.services."home-manager-${name}".serviceConfig = {
+    RemainAfterExit = "yes";
+  };
+}