Trump doesn't understand NATO because it's not a simplistic 'pay this, get that' relationship and if he doesn't understand it then he can't control it and therefore wants no part of it. We know he was already no longer interested in the deal by the time Zelensky arrived, but some sort way forward would have been possible if Vance hadn't deliberately sabotaged it.
European countries could push Russia out of Ukraine but (and a huge one as stepping into a war like that requires all-in) if and only if they are willing to take the risk of the (non-nuclear) fallout as Putin throws whatever he has available at anything within range with the same sort of discrimination as with Ukraine, i.e. power infrastructure, hospitals etc, there's a whole load of other knock-on effects to deal with and it couldn't be immediate but staged.
Amongst other things hopefully the group meeting today can appoint a liaison to translate things into terms Trump can follow, though they still need to break his moronic attachment to false information and Kremlin talking points though since he can't remember stuff he said yesterday (or pretends not to without blinking) it might be a more basic matter of removing the prompters.