Let Ukraine loose its sovereignty? To let them be absorbed into a country they want no part of?
That would just feed the insatiable hunger of Putin, and they would perform yet an other “military training exercise” in the next country. And then the next until there is nothing left than to attack NATO countries, which brings us back to to my second outcome.
The only peaceful option can only be chosen by Putin, by just pulling their invasion forces out. Anything we throw at them is self inflicted at this point.