Some guy on Reddit (with an illustration video):

Saw this online, tried it, and it works beautifully. Basically, I registered the lowest part of my right index finger. That part of the finger sits naturally when you go to swipe up at the phone.

This resolves a major issue I had where I couldn’t easily just look at my phone to glance through notifications on the lock screen. Now, it’s never been easier (shown at the end of the video).

This is arguably better than Face ID. The speed is up there, and the phone doesn’t need to be facing directly at you to unlock, this motion can be done as soon as you pick up the phone.

Tim Hardwick at MacRumors quotes the “arguably better than Face ID” line.

This idea is clever, and it does seem to work if you grip the Duo just right, but the idea that this is better than Face ID is a joke. Copium is a strong drug but it wears off quickly.