I didn't say it was a perfect solution and would be absolutely reliant on the 27 countries actually pulling together and fronting up with cash. However such a force, were it to exist, would have the ability to intervene in Ukraine and other non-NATO countries bordering Russia to challenge Russian aggression and expansionist policies.
The result would be the same irrespective of whether it was a European army, NATO, the Organisation of African States, the WI - if any of them directly interfered and began to roll back Russia's advance, Vlad would not hesitate to go nuclear.
NATO is constrained by it's founding principle of defence of its member states.
Sort of arguing against myself but I do wonder if they hide behind this sometimes. They have been willing to flex this constraint on occasion e.g Afghanistan - Ukraine is much closer to Member States and likely to present much more of a problem, if only from the flood of refugees.