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!