This Is How The Repo I Am Basing This On Seems To Do It

hosts/virt-nix/default.nix

@@ -11,7 +11,7 @@ inputs.nixpkgs.lib.nixosSystem {
     globals
     lix-module.nixosModules.default
     home-manager.nixosModules.home-manager
-    # ../../modules/common
+    ../../modules/common
     ../../modules/nixos
     {
       # something with overlays, I don't get those yet.
@@ -63,13 +63,6 @@ inputs.nixpkgs.lib.nixosSystem {
         extraGroups = [ "networkmanager" "wheel" ];
       };
       nixpkgs.config.allowUnfree = true;
-      environment.systemPackages = [
-        pkgs.git
-        pkgs.vim
-        pkgs.curl
-        pkgs.wget
-        pkgs.vscode
-      ];
 
       system.stateVersion = "23.11";
     }

modules/common/default.nix

@@ -0,0 +1,16 @@
+{ config, lib, pkgs, ...}:
+{
+  config =
+    let
+      stateVersion = "23.11";
+    in
+    {
+      environment.systemPackages = with pkgs; [
+        git
+        vim
+        wget
+        curl
+        vscode
+      ];
+    };
+}