I don't really think of the piano and Poland together, but I can't think of any more remarkable pianists than Chopin and Paderewski (1860-1941). Paderewski was also a very important part of the political history of Poland.

There's an interesting NPR presentation on Chopin at https://www.npr.org/2011/07/18/123967818/the-life-and-music-of-frederic-chopin

-Joe-