IF Germany could make it reliable, then mass produce, fuel, and arm it. Best case scenario they regularly bomb US cities, to the sole effect antagonizing the US people (casualties and lost production will be insignificant compared to what is available). There was way to much industry spread throughout the continent to even contemplate that having an effect. Sure there might be some initial panic, but WWII proved terror bombing can not win you a war, not to mention that defenses will be developed.
IF Germany could produce nukes, then it wouldn't matter since peace will likely be achieved with blasting the UK to hell.