This might be a dumb question, but why are hardware systems required to process payments? If the merchant only needs to input an invoice and then the interaction with the client is via a QR code or NFC, why do restaurants/bars etc. need a dedicated hardware to do that? Wouldn't it be enough with a cell phone that is connected to some other system in the cloud that does all the accounting and inventory? It might be mandatory in some cases to provide a receipt for clients, so I could understand a PoS that prints the receipt, but besides that, I don't see why you need a separate thing. I see this project that looks nice, but how would that work? https://geyser.fund/project/bitcoinizepos Most merchants already have their PoS, I know many actually have 2 different ones, would they buy a third one just for BTC?