Honestly, the question I want to be answered is how haven't the Japanese managed to build their own nuke
by the events of the first season? That's nearly a 15-20 year period of time for Japan to construct a functioning atomic device; Japanese technology shouldn't be trailing behind the Reich at this point. OTL Japan managed to create functioning
submarine carriers. With an Empire that large, no nation shouldn't be able to not procure a nuclear device in under 5-6 years, let alone be trailing behind the Reich in all aspects of technology. Heck, the OTL Japanese managed to develop a
jet fighter engine in WW2 based on nothing but photographs and a single cutaway drawing of a German jet engine.