I bet that is an interesting question:
WI: Nazis got nukes?
Do you see, it took twenty years for the USSR to catch up with the number of nukes that the USA had
Assuming the nazis had nukes, they would launch it regardless of how many nukes the allies have, thus the result would be a way shorter, and way more brutal war, Maybe London, Glasgow and other cities on the UK are nuked, and in exange the most populous parts of germany on this TL would be the lesser populated OTL since the rest would be composed of irradiated ruins