>help the Third reich
The only practical way for the axis to win the second world war that's not through fiat or deus ex machina
is not to start it in the first place, and convincing them to do this would be a hell of a task.
Nuclear weapons plans are nothing if you haven't the fissile material to use in them, and getting that
is the hardest part of building them.
Bonus points though, if your operatives get them not only to not start the war, but convince the rest of the allies that Stalin is the bigger threat. Hell, Churchill hated Stalin far more than he disliked Hitler. So, everyone goes to war against gommunism, and then they'd probably end up with their lebensraum anyhow after Europe got chewed up by the war against the Soviets. Then you could just settle in and watch the slow and eventual progress toward the current year, which would probably end up more-or-less the same but with a different-ish Europe. All roads lead to clown world.