Pixel 4

XDA Developers

Air Gestures

Perhaps the most interesting Pixel 4 leak we’ve seen is the possible use of air gestures, operating the device without having to touch the display. Google’s Project Soli radar chip was first introduced in 2015 at Google I/O, then demonstrated in action working on prototype smartwatch and smart speakers the following year. Indications surfaced in June that this chip might finally be ready for prime time since “skip” and “silence” (mute) media playback gestures are being worked on in Android Q that would require the support of such a chip for the phone to be “aware” of when the user makes such a gesture. While mainline Android Q seems to have a rather limited implementation for exploiting the capabilities of this radar chip, I have no doubt that the development community will come up with some more interesting uses.

I'm really busy, haven't even had a chance to watch this.

Ultrahaptics

That little buzz you feel in your phone when you touch it... and it wants to be clear that you know you've done something is "haptic" feedback.

Ultrahaptics, has come up with a way to make you feel stuff without touching it. (I'm really curious to try this.) 

If true and pure gesture control is going to happen, I think this will be required-- otherwise it will be very difficult for software to figure out what all of our sloppy gestures mean.

This is a part of the whole ecosystem, and without this kind of feedback there will probably be an intermediate step to common gesture control (like the post yesterday.)