Ukrainians have no love for Russkies. I can’t imagine any Russian soldier wanting to die fighting Ukrainians but I can imagine a Ukrainian soldier wanting to kill a Russian soldier in defense of Ukraine.
Western Ukrainians don’t - in the worst case scenario I don’t see Russia going further than the Dnieper River. I think that would be the probable limit of Russian conquests and it would also give Moscow a land bridge to Transnistria. IF there is a war.
Russia is simply to going to avoid Western Ukraine because it would not be welcome there and the costs of occupying it are simply too high to be worth the risk. The West can have it if it wants.