"Germany winning" would have to question the makeup of WW2 as a whole. The US was a powerhouse on a completely different level. The soviets would have collapsed in 1942 or 1943 if the US wouldn't have stuffed their ass full with food, logistical and military supplies. As well as the invaluable contribution of doing bomber campaigns where the USSR needed them. The US sent more supplies to the USSR than to it's own troops on the western front. And if the US would have gotten bogged down for whatever reason, the nukes would jave cemented them as the ultimate victor anyway.
So an alternate history scenario would have to incorporate Germany distancing itself from Japan in the american public eye, and a 180 degree of the american political class. And idk.what would have to happen in Asia for it all to make any lick of sense.
Man, I don't want to get into the extremely controversial weeds of "German WW2 Victory TLs," but...
I do not believe that the Soviets would have necessarily collapsed in 1942 or '43 without Lend/Lease. U.S. aid was extraordinarily helpful to the USSR, sure - tankies love to point out that it accounted for a very small percentage of total Soviet production during the war, but it consisted chiefly of the materiel that was the most difficult to produce (like aircraft), or that most helped other things get to the front lines (like trucks and fuel), and therefore freed up a disproportionate amount of Soviet resources. Without it, there would have been a dangerous gap in production (especially of planes) in 1942 before the new factories in the east could come entirely online, and it would have been touch and go for the USSR for a lot longer than in OTL. And then, even if they did pull through this dangerous period, the increased demands on Soviet labor (and on the always godawful Soviet agriculture) would have resulted in a lot fewer young men able to be rotated away from the factories and onto the front lines. Even in OTL, by the end of the war the Red Army was having some severe manpower shortages, and this would have been much worse without American aid. Still, the USSR was massive in population and resources, and Stalin's bureaucracy was
surprisingly good at mobilizing every last iota of both those in times of crisis. Would it have been enough, though?
But the Wehrmacht, too, was in a desperate bind when it failed to conclusively knock out the Red Army by the onset of winter 1941. The German economy was simply not set up to meet the demands of a long, drawn out war half a continent away, and they were already facing some really severe equipment shortages that impacted their ability to conduct offensives in 1942. I've seen takes by people sympathetic to
both sides that the war was essentially lost for Germany after the Battle of Moscow. And that dangerous gap for the USSR in 1942, where the new factories weren't yet online and they were (ITTL) lacking Western aid would have corresponded pretty exactly to the period when the Wehrmacht was least able to deliver a decisive blow. Still, without the Allied terror-bombing, the African front, or the need to maintain the U-Boat campaign, they would have been able to rearrange their and their allies' economies towards beating the Soviets much more quickly. Would it have been enough, though?
It would have been a much closer-run thing, that's for sure. I tend towards the opinion that Soviet advantages in resources and manpower would eventually have proved overwhelming, and the Germans would still have been driven back, step by step, from the gates of Moscow. But I think there's a very real chance that, sometime in 1946 or '47, with both sides starving and barely able to field an army even as large as one of Napoleon's, a truce of exhaustion might have been called with the front-lines somewhere near Warsaw, in the middle of a Poland even more devastated than in OTL. And then what? Another revolution? In Germany? In Russia? In
both? Very possible. A restarting of hostilities in '51 or '53, this time with a few Fat Man or Little Boy sized nukes getting thrown around? Also possible. Whatever happened, Eastern and Central Europe would have been a horrifically grim place to be. 'Apocalyptic' is not too strong a word.
But it's all pretty pointless speculation. The British government, once engaged in the war, had no intention of coming to terms with the Third Reich unless absolutely forced to by circumstances. Circumstances that were just not going to happen. And Roosevelt was even more ideologically committed to destroying Nazi Germany than Stalin was - the Soviets always felt they could bide their time and wait for the inevitable opportune moment to 'destroy capitalism.'
If you want a TL with a really strong chance of a German victory, your two best PoDs are either something happening in the '30s that puts the U.K. firmly on Germany's side (unlikely), or the Nomonhan Incident going the other way so Japan decides to push against the USSR instead of a (grossly suicidal) attack on the USA (also unlikely).