Kind of hard to do that when there aren't any US cruisers or destroyers in the game yet
I always imagined the foreign navies as something fully developed off-screen and any efforts to "rescue" foreign ships are really just joint operations where they offer you one of their vessels in exchange for certain missions meant to protect their interests.
For example: Graf Zeppelin is offered as a reward for recovering U-47 from her abyssal state but all German U-boats are Submarine Princesses in their abyssal state.