- some fine tuning in the administration of Luhansk and Donetsk
- restoring flow of drinking water into Crimea that Ukraine stopped after annexation
- committing not to host NATO nuclear weapons
Ukraine is a pivot, not the prize.
Putin wants Ukraine, and the Luhansk/Donetsk "peacekeeping" situations were largely manufactured to give a pretext to explain the trucks crossing the border -- which let's be honest he abandoned within less than 24 hours.
The abusive partner analogy again: it's like when (usually a) woman agrees to sacrifice some freedom (her male friends, not socialising with a particular female friend, not going to the gym on her own) because it "unnerves" her partner. It's never asked in good faith, and it always prefigures more sacrifice down the line.
Putin has manufactured these things you think Ukraine could consider compromising on.