the nazis came as far as they did because a ton of peoole greeted them as liberators and joined their new oppressors to fight for a free homeland. You dont do that unless you really hate the empire you are imprisoned in..
People underestimate what a clusterfuck of ethnicities pre WW2 Eastern Europe was. Resettlement after WW2 created much cleaner ethnic maps and arguably the reason we had 80 years of mostly peace (Yugoslavia was last country with mix of ethnicities and wars in 90ies cleaned up it too).