If I was Ukraine I would cede Crimea and the smaller areas in the east the separatists occupied before the war. Those three places are vastly majority Russian populated and thus a likely source of trouble in the future. Focus on keeping the areas populated by Ukrainians, make peace and then militarize like hell, including setting up your own Iron Dome system, to be ready for the next time.
So when do they stop ceding territory? The next time Putin wants a chunk (and you know he will) just give him those too? How about the ethic Russians can go back to Russia if they would rather live under the thumb of a totalitarian quasi dictator.
Let me ask you, would you be ok with Quebec leaving Canada? They are practically ethnic French. Hell their official language is French.