I am very excited for this. I believe the settlement time for this transaction could be very low. 1: NFC to move ecash tokens to merchant device 2a: if merchant trust mint, reissue ecash to themselves. 2b: if merchant does not trust mint, sweep with lightning to themselves. The case for 2b is a little more complicated because the sweep would incur fees that the merchant may want to charge the customer for. Overall though this seems like a super good payments flow, I love it!