It's easier to find smartcard readers with keypads, and use a smartcard. For example see here: https://en.cryptoshop.com/products.html https://en.cryptoshop.com

It's easier to find smartcard readers with keypads, and use a smartcard. For example see here: https://en.cryptoshop.com/products.html https://en.cryptoshop.com/products.html. There are also keyboards (e.g. from Cherry) with an integrated smartcard reader. Note that I haven't tried any of them. But really it's largely enough to have a confirmation system, and that is supported also by the YubiKey 4, for example.