A QR code doesn't power a device, though.
Discussion
But it is a lot less attack surface. Small codebase compared to the usb stack.
USB?
🤔
Yeah, the universal serial bus needs to support everything and the kitchen sink, while bitcoin transactions only rely on small amounts of data to be transferred in order to be valid.
So in this case: keep it small is preferred.
But precisely using NFC avoids the need for USB, if I understand it properly.
But I can't see what it actually transmits. I probably can still verify it, but a qr code is more straight forward and more static: I can check the content with multiple devices while being sure that it has not been changed as I would notice it.
Nfc is invizible.
Nfc is invizible communication between both parties, so it makes it harder to verify their behavior as they could signal eachother to make up rules. For example, device A could signal to device B that once it loses connection, it creates a dummy transaction, and once it reconnects, it creates a malicious one.
Because you likely verify with seperate devices, you will probably loose connection with one to make a connection with the other verification device, in the mean time the host device or the "hardware wallet" could change the transaction to a normal one to hide the malicious intent.
But I can be wrong.