What are some good two factor methods for logging onto your Mac? What are some options I can deploy to require users to use multi factor authentication when logging onto their Macs. In the same fashion you use your password and Google Authenticator code to log into Gmail, GitHub, Slack, etc., is there something for logging into your Mac.
How about something like Knock?  http://www.knocktounlock.com
It's not exactly the same as looking up a time-dependent code, but does require the 'second factor' in order to unlock.

The neat thing is that many apps (I think Knock included) run on Bluetooth, so when you walk away from the Mac and the BT disconnects, it automatically locks up the machine.