If I recall correctly there are some polish-inspired maps. There are at least two of them somewhere on the repo. Maybe if the devs find it interesting enough, they might make a polish map. I'm guessing they would make Japan first though, considering how there's a map where each car comes from natively (Wentward, Bruckell, Gavril = USA | ETK = Germany | Civetta = Italy) so I kinda see a pattern here.
Countryside in Poland: https://www.beamng.com/resources/countryside-in-poland.12333/ Polish Mountains: https://www.beamng.com/resources/polish-mountains.7978/ Polish Roads: https://www.beamng.com/resources/polish-roads.5846/