>>511376939
oil
either way they get steamrolled early game until their states are brought to heel and the fuel starts flowing
after which point you have the unending tide of russian armor to deal with

there is no conventional way for germany to beat the soviet union when mobilized
would have needed some kind of destabilizing effort, maybe turning some of the eastern states against russia
it doesn't really matter what you do as germany in that scenario, if the ussr manages to establish it's logistics network you lost already because total war is numbers and they have more