Now scientists are looking for his pavement observatory in Frombork; and there are remains of his observatory (written in chalk on the wall) in the castle in Olsztyn. As both those cities were back then in Poland, under a bishop, and Copernicus was a church canon, and helped protect the province against the Teutonic Knights - well, fully Polish, despite the German part.
Where did he write his famous work? In Frombork, where I once was. In the years 1510-16 and 1522-43 he conducted research there and wrote his "De revolutionibus...", died in 1543 and was buried at the cathedral. His grave was found several years ago. So if he spent the most important years in Polish Frombork (a far northern town with a cathedral, very quiet), he's one of us. He was a subject of the Polish king, Polish bishop.
But does that mean that Poles are some pagans, opposed to the Vatican teachings? Well, no, maybe this was his Germanic part, early Lutheranism. Protestantism never took real root in Poland.