If the European nations brought their Iraq and Afghanistan forces to Ukraine, they’d probably retake it by years end.

If you could guarantee Russia wouldn’t lob nukes, they probably could make an incursion strike into Russia to capture Moscow fairly quick, especially if Russian forces were divided along the lines like with Kursk with diversionary tactics.

I think the goal is to wait everything out though hoping Russias economy will implode, or until time that everyone gets their military up to snuff. It seems like Poland was the only one preparing for the last 10 years mind. Poland absolutely does not want to return under Russian rule. None of them do! Which is why they all joined NATO.