Hitler was counting on the fact that the non-Russian peoples in the USSR would end up supporting him — the Aryan peoples, especially.
Eventually, there were SS units comprised of men from all the conquered USSR territories like the Ukraine, Latvia, Lithuania, and Estonia. They fought long and hard for Germany. Some were evil and also persecuted the Jews and helped round them up. Most of the conquered peoples, not surprisingly, just laid low and tried to survive until the end of the war.
Curiously, the one ethnic group that embraced the German invasion wholeheartedly was the Cossacks. It didn’t really happen until 1942, when the German Army occupied Crimea and nearby lands, but the Cossacks became very fierce, brave, and loyal parts of the German military machine.
“Curiously, the one ethnic group that embraced the German invasion wholeheartedly was the Cossacks.”
Looks as though the Cossacks are both Russian and Ukrainian. I can certainly understand the Ukrainian Cossacks jumping at the chance to help Hitler, considering what they had just gone through.