got it working even more

modules/terminal/default.nix

@@ -9,6 +9,7 @@
   imports = [
     ./kitty.nix
     ./ranger.nix
+    ./fish.nix
 
   ];
 }

modules/terminal/fish.nix

@@ -0,0 +1,22 @@
+{
+  config,
+  lib,
+  pkgs,
+  ...
+}:
+
+{
+  options = {
+    terminal = {
+      fish.enable = lib.mkEnableOption "enable fish";
+    };
+  };
+
+  config = lib.mkIf config.terminal.fish.enable {
+    programs = {
+      fish = {
+        enable = true;
+      };
+    };
+  };
+}