Google is working on new gestures that require an “Aware” sensor, possibly for the Pixel 4

In summary, Google is working on a pair of new gestures in Android Q. The two new gestures are called “Skip” and “Silence” and they’re likely controls for media playback, although the gestures are far from complete so there’s no way to activate them to test for ourselves. Furthermore, the new gestures require a new “aware” sensor that isn’t defined on any current Google Pixel device, so it’s possible that the new gestures will debut on the Pixel 4 if it has this “aware” sensor. Given what we know of Project Soli, it’s possible that the Soli radar chip will provide this new “aware” capability.

XDA-developers report.