Pierogies, that alone puts wm in a prime spot. I'm not really up on the regional specifics of what I generally lump in as northeastern Europe food, which a lot of it slaps. Beets rule.
Every time I have wanted to eat at a Polish restaurant they have had literally zero vegan options so I have no thoughts.
Frizen supermarket pierogis are good if you treat them right and accompany them with curry powder, vegan sour cream/yogurt, and rye. But I am not sure how authentic they are.
There’s a Polish place in NYC that managed to make me enjoy cabbage so I’d say the food’s pretty good. I also liked Madame Anastasia from season 2 of The Unsleeping City, but I don’t know how faithful a representation of Polish culture she is.