I think you missed the point war with the west wasa a side project , nazi idelogy of lebensraum targeted the lands in the east as new settlers paradise. Have you ever heard of Ensatzgrupen ,death squads there were never any on the west front .
Obersalzberg Speech prior to invasion of Poland.
''
Our strength consists in our speed and in our brutality. Genghis Khan led millions of women and children to slaughter – with premeditation and a happy heart. History sees in him solely the founder of a state. It's a matter of indifference to me what a weak western European civilization will say about me. I have issued the command – and I'll have anybody who utters but one word of criticism executed by a firing squad – that our war aim does not consist in reaching certain lines, but in the physical destruction of the enemy. Accordingly, I have placed my death-head(totenkopf) formation in readiness – for the present only in the East – with orders to them to send to death mercilessly and without compassion, men, women, and children of Polish derivation and language. Only thus shall we gain the living space (
Lebensraum) which we need. Who, after all, speaks today of the annihilation of the Armenians? '''
Japan might have helped them if it was nto fighting the war with US , that is why almost till Stalingrad soviets kept almost half of the army in the east. The fought wars with Japan number of times and feared Japan might strike while they were fighting the Germans.
This is what Adolph and co. aspired to. War in the west was just a small warmup for genocidal march into the east.
They wanted to settle the new lands with
Wehrbauer, a soldier–peasant who was to maintain a fortified line of defence. Why the east , because no one could block , sanction ,blockade Germany if it possesed own resources and was independed of the international tradeways.