It definitely sounds like a cool gift, but I do see some flaws in the idea. How would someone tell the difference between a real device and a clone? I think an engraved QR code would be an awesome feature and it would allow for one to verify the amount on the chip. If the required security was added to the device, I could see it being used in money laundering.
from my current understanding, when you plug it to an usb on computer (or a phone) you can verify the amount on it. also they have blinking leds. if it blinks red it means that the key was reviled.
my main concern is what if removing of the chip does not do the job of reviling the key.
i am in a bit short of time, so no time to do the research of specifics.