The pixel pinch phone body for the Google assistant. Boy how I want that feature badly when I was using OnePlus 3T. It felt like one of those double tap at the back of iphone little niche thing.
I really like since it give the user different kind of input to interact with the phone quickly. We have the double tap and holding for power button, double tap the top of the screen, the screenshot combo button and etc. Same like the interface for controlling your wireless earbud.
The pain for installation/maintenance/replacement for that input must be a nightmare though.