>>518654919
They still should have waited a little longer.
The smartest play would have been agree to invade Poland with the Russians and then not done it.
Instead, they should have funelled weapons to fascist sympathizing partisans in Poland to delay the soviet advance while publicly denouncing the soviets as warmongers and an existential threat to western civilization.
They could then declare war on Russia and send troops into poland (securing danzig on the way of course) to contain the soviet menace while demanding France and Britain honor their commitment to defend polish sovereignty.
They could then reinforce this ad hoc alliance by funding fascist political movements in France, Britain, and the US, which were all growing prior to the war.
The presence of a shared enemy would foster the rapid rise of pro fascist sentiments in these coutries.
If they had time it right, they could have let the poles take the brunt of the soviet advance and then wiped out much of the soviet army with a surprise counter-attack.
This would leave them with a tentative alliance with the French and British, an occupied poland (someone would need to restore order of course :) ), and a shattered Russia on the retreat.
America and Japan would have went to war over the oil one way or another, but if Germany just stays out of it then that leaves America to fight pretty much the entire pacific war alone.
They would still win, but they wouldn't really have the extra resources to get involved too much in europe.
The end state of the war would then be another cold war, but this time between the Americans and a fascist version of the EU.