maybe modifying how the attrset merges in config will help

flake.nix

@@ -16,7 +16,8 @@
     in {
     lib = builtins.import ./lib.nix { pkgs = nixpkgs; };
     nixosModules.fooud = { pkgs, lib, config, inputs, ... }: {
-      options.programs.fooud.enable = lib.mkEnableOption ("fooud") // { default = true; };
+      options.programs.fooud.enable = lib.mkEnableOption ("fooud")
+        // { default = true; };
       config = lib.mkIf config.programs.fooud.enable {
         environment.systemPackages = [ package ];
       };

lib.nix

@@ -33,15 +33,34 @@ let
         };
       };
     in
-      dest;
+      {
+        config = config;
+        dest = dest;
+      };
 in
 let
   gitUpdater = config: { git, keys, dest, check }:
-    defaultUpdater { git = git; keys = keys; dest = dest; check = check; config = config; };
+    (defaultUpdater {
+      git = git;
+      keys = keys;
+      dest = dest;
+      check = check;
+      config = config;
+    }).dest;
   fsUpdater = config: { path, dest, check }:
-    defaultUpdater { path = path; dest = dest; check = check; config = config; };
+    (defaultUpdater {
+      path = path;
+      dest = dest;
+      check = check;
+      config = config;
+    }).dest;
   urlUpdater = config: { url, dest, check }:
-    defaultUpdater { url = url; dest = dest; check = check; config = config; };
+    (defaultUpdater {
+      url = url;
+      dest = dest;
+      check = check;
+      config = config;
+    }).dest;
 
   lib = {
     inherit