There's no reason they couldn't add a full secure enclave on a USB based keyboard with TouchID.
Register your fingerprints into TouchID, they are stored securely on the keyboard, with some secure communication between keyboard/computer... now you can easily log in and or do Apple pay.
Register your fingerprints into TouchID, they are stored securely on the keyboard, with some secure communication between keyboard/computer... now you can easily log in and or do Apple pay.