It's a proof of concept, and at least passively interesting. Of course, I didn't see a "decline" button, and without a power button it could be an issue.. btle could be sufficient with a screen sleep.
Also no idea how to add currency to the wallet... that could be another issue.
I saw another diagram of the device where it has two buttons -- one to accept (pay) and the other appears to be a power cutoff switch. I'm thinking that power cutoff will be the payment rejection button.
> Also no idea how to add currency to the wallet
If you get past the crowdfunding page, you are assigned a *.firefly.eth "ENS" name. This corresponds to a wallet address. So, the same way you add currency to any other wallet. (How does it know that it has an available balance, though...)
Also no idea how to add currency to the wallet... that could be another issue.