Seize Kaliningrad back from russian control. Purge or expel all active putin sympathisers and bring to international justice any who have committed crimes against the population during the russian regime. Replace all elements of their governance and influence. Confiscate their assets where appropriate.
Place temporarily under UN or other international administration, such as a coalition of Poland and the Baltic states. Establish democratic mechanisms and oversight to enable free and fair elections. Kaliningrad was named by Stalin, a new name should be approved by referendum. Redistribute confiscated russian assets.
Decommission and remove offensive capability, especially nuclear, under the oversight of appropriate international bodies, including the ICNND. Align Kaliningrad with NATO and establish appropriate defensive policy and capability, supported if appropriate by a permanent NATO presence.