Getting a mag strip reader (MSR) isn't hard and a USB can be found for under $20.
So you read out the tracks and get the data.
You would need to input the amount. Keypad and 7 segment display should work there. While smart watches aren't ok, I suspect that the some electrical cash register is acceptable... and then...
Wait a moment, if they've got an electric cash register they've got the ability to have a MSR.
Anyways, let's assume that the 7 segment display for input of the amount is acceptable. If not... Nixie tubes?
Once the amount to charge is entered, and the card is swiped through the MSR, a receipt printer with the result is used (though they might have issues about that since thermal paper receipts often have BPA https://www.pca.state.mn.us/business-with-us/bpa-and-bps-in-... )
Anyways, result of the transaction through whatever payment processor happens and is sent back to the pi (no screen) that then prints out the result.
Sending credit card number to a payment processor from a MSR is no more difficult than sending it to the same processor from hand entered (for example, online). You might have a higher fee rate, but it's not difficult.
So you read out the tracks and get the data.
You would need to input the amount. Keypad and 7 segment display should work there. While smart watches aren't ok, I suspect that the some electrical cash register is acceptable... and then...
Wait a moment, if they've got an electric cash register they've got the ability to have a MSR.
Anyways, let's assume that the 7 segment display for input of the amount is acceptable. If not... Nixie tubes?
Once the amount to charge is entered, and the card is swiped through the MSR, a receipt printer with the result is used (though they might have issues about that since thermal paper receipts often have BPA https://www.pca.state.mn.us/business-with-us/bpa-and-bps-in-... )
Anyways, result of the transaction through whatever payment processor happens and is sent back to the pi (no screen) that then prints out the result.
Sending credit card number to a payment processor from a MSR is no more difficult than sending it to the same processor from hand entered (for example, online). You might have a higher fee rate, but it's not difficult.