I can’t help but think a lot of this posted so far is viewing it through a post-‘45 lens. In the PoD as posted by the OP, the Nazis have been defeated in 1940 or ‘41. This implies a stopped and reversed invasion of France and probably WAllied (at least) troops on the ground in Germany. I can’t see the Nazis shitting a brick and surrendering immediately if the French cross the border, so I imagine you’ve either got an Allied offensive that drives deep into Germany or a General’s coup once Hitler’s bluff has been called (as they would see it).
Therefore, the idea that Hitler and the top Nazis would be executed out of hand (unless they’re done for in the coup - if it happens) seems to me to be a little unlikely. Up until the end of WWII and the revealing of the Holocaust, the idea of putting leaders of nation states on trial in an international forum had (to my knowledge) never been touted before. The Nazis in ‘40/‘41 hadn’t really got their worst excesses into full flow - especially if this is pre-Barbarossa.
Maybe some Nazi/SS/Gestapo types are tried and executed - for murder, or “exceeding their authority”, but I can’t see worse than jail time for Hitler and Co., probably to be served in Germany itself.