Pilsudski believed in country, building a independent prosperous Poland for all people within it's borders.
actually Piłsudzki envisioned a confederation of Slavic and Baltic States between Germany and Russia - he was a supporter of a free Ukrainian state for example (after defeats in 1920 Ukrainian state was not quite viable though) - furthermore had Poland really wanted it it could have conquered the whole of Lithuania not just the Vilnius region which was inhabited by a huge Polish majority - perhaps it was a political mistake even to claim the Vilnius region but Poland was not bent on subjugating the Lithuanians - haven't heard of Piłsudzki's views of a free Beloroussian state but I guess they were pretty similar to those of Ukraine - sadly the newborn Czechoslovak state (especially it's elites but not solely) were too russofile and their leadership decided upon seizing Zaolzie which was inhabited by big Polish majority and then implemented strict czechization/bohemization policies there - this spoiled the Czecho-Polish relations seriously