Fortunately, the Nazi’s couldn’t figure out an A-bomb before Hitler nuked himself.
There is a story about a Nazi state banquet in 1941 or so. A Nazi big shot (Goering?) was sitting next to a university professor and tried to make small talk.
“How are things in the Physics Dept, herr Professor?”
“We have no Physics Dept, herr Reichsfuhrer. They were all Jews and all have emigrated to America.”
Many of the great nuclear physicists in Europe were Jewish. Mrs. Enrico Fermi was also Jewish. They fled Europe, Germany in particular, in the 1930s.
Never count on your enemy being a genocidal maniac and chasing away his best scientists ... but be grateful when it happens.