It would be tough, really tough.
Most popes since 1000 or so have been Italian, and the others have been (mostly) from France or the German parts of the HRE. A few from Iberia.
Poland, for most of its history was pretty peripheral to Europe, and not nearly as important as the other major states that got their guy elected.
The fact that one of the Iberians was Portuguese, and that Adrian IV was English does suggest that a peripheral region CAN get a pope elected from their territory, but it's going to be tough.
Well. That's why it's challenge, eh?
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How about some major bishop who gets a reputation for 'converting' thousands of Orthodox in the PLC (Ukraine, Belarus). Maybe an earlier 'uniate' Byzantine Rite church, and with a Polish Bishop spearheading the change, not a King.