Ukies must rebuild and expand their domestic weapons production ASAP.

They're doing what they can with existing capacity and also innovating (e.g. all that drone stuff) but actual expansion takes time.

Take the Rheinmetall joint-venture as an example: The factory is slated to open in two years or so which is fast, but even then by then the war might already be over. OTOH Ukraine will have a very modern factory and Rheinmetall can basically file the whole investment into their advertisement budget as Rheinmetall itself will indeed be responsible for protecting the factory.