A smart ring that does web of trust key signing during a literal handshake 🤝
I think that would convince me to make one with some tiny chip like Xiao samd21. That would have to be called SIGNET. Because you know... it's for signing.
It would probably also have a form factor of a signet because the chip is a square, that would be place where normally a seal would go. And the NFC coil would go around the finger.