Hello, I am a trans woman living in on of the bigger cities in Poland!
Generally, if you live in one of the big cities you should be fine (most of the time). I’m am yet to have any issues, however I do avoid wandering alone at night and sketchy streets in general.
Most of the time even people I know are not tolerant will not give me too much trouble, however this might be very subjective and might vary significantly.
Sentiment online also seems to be not the nicest, and seems to be shifting a bit against our eastern friends due to political frictions and certain country doing some meddling, so I don’t know what to say future-wise. It is what it is.
In terms of communication, I feel like most young people know english at least a little bit, and a lot will know it at communicative levels, however older people will most likely not know a word. It should not be a problem at all at restaurants, but might be in a grocery shop or when asking for directions at a bus stop. As a native polish speaker it might also be a bit difficult for me to say, as I don’t really try to talk with people in english here lol
As for vegan stuff, well, selections are not the best, but it keeps getting better. Restaurants will often have at least 1-2 vege options, but it’s not a given and I always check menu before going. Afaik Warsaw is a bit better for this, but I’d still advice to make sure you’ll have anything to eat before going :D
For groceries Lidl seems to have best selection of vege stuff out of the ‘common’ store chains, but that is still not very wide. Luckily you can get almost everything on allegro (think amazon, but polish), so that works quite nice for some harder to find stuff you might need for cooking (as long as it’s packaged ^^).
Uh, there are some people who “hold a grudge”, but I wouldn’t expect that to be a real issue. I met a lot of people from Germany at work (automotive industry) and sentiment is generally positive, I don’t think I ever heard of any incidents or complaints from them.