I've worked in payments, and it's tough. You would need to be a merchant bank (ODFI) to control ACH payment access, and the US govt. doesn't normally grant ban

I've worked in payments, and it's tough. You would need to be a merchant bank (ODFI) to control ACH payment access, and the US govt. doesn't normally grant banking charters any more, as all the YC batches have learned the hard way. So you'd have to buy an existing bank. But Visa and Mastercard still wouldn't process cc payments.