At some point you can be antiwar all you like it’s not in your hands. In this case it’s puttin that need to be antiwar, and as long as he isn’t, Ukraine or Europe cannot be antiwar. It’s sad, but a harsh reality. You need peaceful neighbors to be at peace.
Russia won’t ask for this deal. This was what they had in 2014. Would they have not started the fu scale invasion, they would have Crimea still, and the West would still think Russia is reasonable. They started the war to get the dombass fully, to put a puppet on the government, and to make a safe zone around the sea.
What you’re suggesting would mean the war was entirely useless to russia, which I doubt they can afford to settle for.