Add top for building

flake.nix

@@ -90,5 +90,14 @@
           }];
         };
       };
+      # Convenience output that aggregates the outputs for home, nixos.
+      # Also used in ci to build targets generally.
+      top =
+        let
+          nixtop = nixpkgs.lib.genAttrs
+            (builtins.attrNames inputs.self.nixosConfigurations)
+            (attr: inputs.self.nixosConfigurations.${attr}.config.system.build.toplevel);
+        in
+        nixtop;
   }; 
 }