Add a steam deck nix config.

nix/steam_deck/configuration/flake.nix

@@ -0,0 +1,36 @@
+{
+  description = "My system configuration";
+
+  inputs = {
+    nixpkgs.url = "github:nixos/nixpkgs/nixpkgs-unstable";
+  };
+  outputs =
+    {
+      nixpkgs,
+      ...
+    }:
+    let
+      system = "x86_64-linux";
+      pkgs = nixpkgs.legacyPackages.${system};
+    in
+    {
+      packages.${system}.default = pkgs.buildEnv {
+        name = "default";
+        paths = [
+          pkgs.emacs
+          pkgs.mg
+          pkgs.steam-rom-manager
+        ];
+      };
+
+      formatter.${system} = pkgs.nixfmt-rfc-style;
+      # formatter.${system} = pkgs.alejandra;
+    };
+
+  # nixConfig = {
+  #   experimental-features = [
+  #     "nix-command"
+  #     "flakes"
+  #   ];
+  # };
+}