Comment by hkt

Visa and MasterCard, for a start: if a bank issues any kind of commonly accepted debit card to someone who is sanctioned then what is at stake is that bank's ability to continue issuing those cards. Realistically, the bank would be destroyed by being excluded from payment networks and card issuance. So only very little banks that don't interact with anything American (you might manage this with a credit union in the UK, potentially) would be your best bet.