...Ukrainian jets might be (I presume at least Block 30/32C/D's?).
If the Euros are going to supply them, which is what is being proposed right now, they would F-16AM/BM MLU birds which are aircraft built for the Belgians, Dutch, Norwegians and Danes in the 70's-80's and upgraded 20 years later with more modern equipment. All four of those air forces have bought/are buying F-35's to replace their F-16 fleets and could transfer some of their aircraft to Ukraine, if they have any airframe life left.