In addition to this, I’d like to suggest Authy’s OneTouch Login feature. But as the dev replied, Authy has been charging fees to use this feature. (Just as told here. Please check the comments.)
So I guess the only option we have that is “more convenient” to instant login is with Duo’s push notification on mobile as a premium feature.
That’s a nice feature to have, in my opinion, but I guess it wouldn’t be available so soon.
EDIT: This might be a duplicate. More discussion about TOTPs here: