update todo

nixos/virtualbox.nix

@@ -0,0 +1,9 @@
+{ config, ... }:
+let username = config.var.username;
+in {
+  virtualisation.virtualbox.host = {
+    enable = true;
+    enableExtensionPack = true;
+  };
+  users.extraGroups.vboxusers.members = [ username ];
+}