Your challenge is simple, have the Weimar republic survive the 1930s and find a way for it to stabilize and be in ww2. Obviously with a different instigator. Perhaps the Soviet Union?
Hitler gets killed or incapacitated in the Munich putsch attempt. The Great Depression occurs on schedule, the NSDAP vote fraction is reduced to the die-hard 7-8% without Hitler's oratorial abilities, the differential goes mainly to communists in the (also otherwise severely modified in comparison with OTL) 1932 elections. The conservative and Völkische do not accept it and attempt to violently suppress the communists, who resist, resulting in a German civil war. The Soviet Union actively meddles in the war on the Communist side, despite several ultimatums from UK and France to stay out; with Communists in Germany close to winning and Soviets emboldened by their success in Germany trying to do the same in other parts of the world (e.g. Manchuria/Korea), a war between a Soviet/German alliance (with Poland probably either split again or finlandized / forced to join the alliance, or else) and a French/Japanese alliance with british backing.
Italy is who promise more, they're weak oportunist as OTL.Wouldn't italy be in that French-Japanese alliance to?