No. I love him but no. He needs to stay there. We all do. We have no place in any living universe anymore.
That wouldn't work. Kryptonite only works on us if it's from the same universe, and my Krypton didn't explode. It took me forever to find out, but it got swallowed by its sun. If I do get possessed, whoever is fighting me needs to go for whatever weaknesses the demons have.