My thoughts on the subject
I always assumed if Hitler had the Bomb in time, he would
have used it, so therefore the engineers never got far enough.
They sure used the V-2 rocket enough, despite its late entry
into the war, along with the first jet fighters.
Perhaps they did have at least a test bomb, but like his
general who refused to destroy Paris in the wake of the
approaching Allies despite Hitler's orders, whoever had the
Bomb refused to use it as well on the grounds that it
would have been a pointless waste of lives.