Crimea was purchased by Russia from the OttomanTurks. It was part of russia for longer than the US is a country. A Ukrainian USSR Premier took it in violation of the USSR constitition and gave it to his own “Republic” in the 1950s. (Kruschev) We should support Russian claims to Crimea since it was purchased since that makes it difficult for Russia to saber rattle about reclaiming Alaska, which we purchased!
Earlier, in the 1920s Lenin moved parts of Russian territory into the Ukraine. After WWII Stalin seized parts of Poland and moved them to the Ukraine. Russia still holds parts of Poland, Kalingrad (Formerly a Prussian city.) Include those seized territories in Poland in the discussion for territories in the the Eastern Ukraine. (let the Ukraine AlSO give back the illegally seized parts of Poland Stalin gave to the Uks.)
Leave Odessa and nearby Black Sea coast to the Ukraine since they will need to ship their grain to the world.
Territorial grievences: how far back do you want to go?
https://en.wikipedia.org/wiki/Russia%E2%80%93Sweden_relations
To be clear, the Ukrainians are corrupt as the Russians and we should not be spending any money on them or getting drawn into a war with Russia.
The Kaliningrad district was part of East Prussia until 1945--German-held for centuries. I don't think it was ever part of Poland.
The post-1945 border between Poland and the USSR runs fairly close to the Curzon Line proposed after WWI by Lord Curzon. There were some Poles living to the east of that line but most of them would have fled or been expelled in 1945. There’s no benefit to Poland to seek the return of that territory. (Meanwhile a large part of western Poland was German until 1945...the Poles are better off keeping the existing borders although if it were up to me I would split the Kaliningrad oblast between Poland and Lithuania.)
So your point is that if some territory was purchased by some country no matter how long time ago and no matter how much historical events (wars, new country formations happened since), then anyone claiming to be an “inheritor” deserve to claim their rights on the said territory. According to your logic, modern Russian Federation is the same country as Soviet Union, which was the same country as Tsarist Russian Empire. Dare I remind you that those three countries exist(ed) at different times, had entirely different social, political economic, demographical and yes, vastly different territorial setups. To equate them and make grievances based on history is a sure recipe for disaster we observe today. And that puts you personally on the same level with Putin as it was one of his justifications for Crimea annexation. Congratulations!
P.S. Good luck to Putin with saber rattling over Alaska...