airpig:-
it would have taken time but it was doable
Which of course was what the Manhattan Project was all about, defeating a Nazi Germany that had been given time to develop and use a nuclear device. Given that it wasn't given the time, Truman used his bombs instead to save Allied lives (and many more Japanese ones) being lost in an invasion of Japan.
German nuclear weapon research has always been downplayed, but if Hitler had years rather than months left to get there I see no reason to doubt he would have succeeded. You only have to consider the technical lead he had in rocket, jet, and submarine propulsion at war's end. Mercifully that extinguished all of his various lights of perverted science, which had been greatly dimmed by the Strategic Bombing Campaign. That of course is a continuing bone of contention here at dear old Aunty PPRuNe...