They were working on a transatlantic bomber and escort fighter.
ME-354 and -355, if I recall correctly.
Their version of the B-36.
Don’t forget the Germans historically have been fairly inventive and good at building armaments.
They were, but again - they were far from developing it when the war ended. Not only would the Germans had to have developed an atomic bomb, they would have also had to develop a strategic bomber to carry it.
And that’s assuming a dolittle like raid.