There's a 25% tax on gambling winnings in Poland which pretty much cleared out the gambling market when it was introduced. All the exchanges - smarkets, betfair etc left Poland and don't allow access from Poland.
Whatever your plans are will have to factor in a 25% tax on winnings. This is based on residency (I think), so even if a Pole, located in Poland gambles elsewhere, i.e. by VPN elsewhere i.e. the UK, they still have to pay tax on winnings.