default.nix

@@ -4,6 +4,7 @@
 , rustPlatform
 , makeWrapper
 , mpv
+, wrapped ? false
 }:
 
 rustPlatform.buildRustPackage rec {
@@ -36,7 +37,7 @@ rustPlatform.buildRustPackage rec {
     };
   };
 
-  postInstall = ''
+  postInstall = lib.optionalString wrapped ''
     wrapProgram $out/bin/greg-ng \
       --prefix PATH : '${lib.makeBinPath [ mpv ]}'
   '';

flake.nix

@@ -35,7 +35,7 @@
     apps = forAllSystems (system: pkgs: _: {
       default = self.apps.${system}.greg-ng;
       greg-ng = let
-        package = self.packages.${system}.greg-ng;
+        package = self.packages.${system}.greg-ng-wrapped;
       in {
         type = "app";
         program = lib.getExe package;
@@ -63,6 +63,9 @@
     packages = forAllSystems (system: pkgs: _: {
       default = self.packages.${system}.greg-ng;
       greg-ng = pkgs.callPackage ./default.nix { };
+      greg-ng-wrapped = pkgs.callPackage ./default.nix {
+        wrapped = true;
+      };
     });
   } // {
     nixosModules.default = ./module.nix;