By August 1945 the Japanese would have died even if no bombs fell - from starvation. That IMHO would not have stopped the Japanese leadership in ordering a mass suicide attack on an invasion but the nukes convinced enough to say "enough is enough". But what really brought Japan to its knees was not the nukes (or the conventional bombings) but being litterally cut off from any import, incl. food.
I.e. like Germany?
The real difference was another one you did not see, that Japan was finally facing the Soviets, too, in Manchukuo. Not only they knew their last army would be steamrolled, but also that the final, delusional hope that the Soviets would be, if not an ally, at least a sympathetic neutral, was gone.
But before saying that such a factor does not exist in this ATL, we would need to know how it is that Germany is "doing better" in this ATL. It is entirely possible that there is an eerily similar parallel here, too.
And regarding "not going to happen" - so they said at Tjernobyl or about Titanic - there is always a risk.
Oh, sure. Have you checked up the number of redundant fuses? There were four radar proximity altimeters, each able to work on its own, plus two pressure-based altimeters. in any case, impact with the ground would also be enough, for the Little Boy design, to push the two masses together, achieving criticality. I'm not sure this would happen at the intended speed, thus the yield might well be lower than expected - but the bomb still goes boom.
There always is a vanishingly small statistical chance. Is it worth our time discussing a 0.0001% scenario? Come on.
The Soviets started their nuke project way behind but it only took four years to have their nukes, and I don't see why the Germans not could do it much faster once the first had been tested or dropped.
Because you don't know that the Soviets had insider information, while, as mentioned, what the Germans would learn from the first bomb is that the principle, contrary to what they believed, did work.
Anyway, the German war production late war was so dispersed because of the conventional bombings that not even nukes would have impacted output significantly ...
Of course they would, in the same way that conventional bombing did affect dispersed production.
Conventional bombing targeting marshalling yards, rail lines, tunnels, bridges, and trains, as well as cities that were rail nodes, the Allies made sure that fighter engines built at tunnel plant A would not reach airframes built at secret factory B, and if they did, they still wouldn't receive instruments from remote workshop C or fuel from hidden hydrogenation plant D.
Now, nukes would work exactly like area bombing under this respect. You want to send parts by train along the main rail in the Ruhr valley, i.e. through Essen - oops.
Area bombing - and by that I mean both British city bombing and US "precision bombing" that happened to target marshalling yards in the midst of cities - also had another effect. Consider Dresden. There were many small factories, plants and workshop producing war materials, and they were spread out throughout the outlying residential areas and even in the immediate countryside. Many of those suffered light or no damage at all.
But guess what, after the bombing, they still did not produce a lot, because workers did not show up.
No offense intended, but as always, discussing alternate history is more satisfying when one knows actual history well.