So we use DUO for 2FA at work and it uses push notification authentication as the second factor for 2FA. It's so quick and easy! I enter my username and password, get a push notification on my phone, tap Approve, and that's it! No fiddling with codes from an authenticator app or SMS, and definitely much more secure than SMS authentication. It also doesn't introduce the complications U2F does (specialized hardware, a browser that supports it).
Google already implements it for both Android and iOS with Google Prompts, Authy already provides support for it also on both Android and iOS using Google's and Apple's push channels. So why are we still using SMS's as the main form of 2FA (especially at BANKS)? I mean, it's so user-friendly, I don't see why the movement to get rid of passwords hasn't hailed this as the replacement for passwords when using only 1FA; it seems viable even for that.