Axis powers could have won WW2 comfortably in only one scenario - Uranverein project under Heisenberg beat Manhattan project under Oppenheimer to build the first atomic bomb.
During the "lightning war" Germany did not need any wonder weapons - they took Europe by a series of blitz victories. When Soviets fought back and Pearl harbor happened, the Nazis were fighting a attrition war and were outfought by logistics, financial planning and a superior supply chain. They were outspent in the war and simply ran out of resources running insane military projects - jet engines, rockets, alternative fuels etc. The Japanese were boxed in after the German defeat and the Soviets turned their attention east. Japanese theater of war was shortened by the atomic bombing, else the Soviets would have marched to Tokyo. The only way that the Axis powers could have turned the tide in this game was if the German atomic weapons project Uranverein succeeded in producing nuclear warheads. Thankfully this did not happen because of a series of poor choices by German Army ordnance and high command which diverted resources to the V2 rocket project though they had a vast team of capable physicists. The theory that the German scientists sabotaged their atom bomb due to moral dilemma is flawed. They would have succeeded if they had chosen graphite instead of heavy water and had more resources at their disposal in the early 40s before Germany came under attack.
If such was the case, the first thing to come to mind is that United Kingdom would have been the island nation that was nuked, not Japan. The naval blockade and land invasion of the Unites States is silly, the axis powers would have forced a ceasefire/treaty using the atomic threat. The Soviets would have been forced to submit under the same atomic threat. Europe at the mercy of Nazis. Britain a lump of smoldering bricks. African territories of the Crown handed over to Nazi control. China overrun by Japanese forces. India a German trading post under the leadership of Bose. United states turns a blind eye to all this and signs a treaty. Not a pleasant thought. The world would be a vastly different place if Axis powers had won, and the consequences are many.