That’s good info to know, @Wojtek_Traczyk . I’ve been learning a lot about international payments and shipping and taxes since starting this project, we want to make it as global-friendly as possible.
I’ve about 99% decided to make the project open source at this point, but we’ll sell premium extensions like various payment gateways. I would imagine that przelewy24 would end up as one of the paid extensions, I plan to only give PayPal and Stripe away for free.
Once we’ve locked down the Kart Payments API, you’d be free to develop the gateway extension yourself, if you’re interested. I’ll certainly help you out, and then you could make some money reselling the extension.