https://thenextweb.com/security/2019/10/18/pixel-4s-face-unlock-works-even-if-youre-asleep-or-dead-and-thats-a-problem/

Google’s new Pixel 4 smartphone doesn’t have a fingerprint sensor. Instead it relies on “Face Unlock,” a proprietary facial scanning system similar to the one found in Apple’s Face ID. Early reports show a system that works well, perhaps too well, in fact, according to some security experts.

To unlock a Pixel, the operator must hold it up to their face while onboard cameras and sensors go to work scanning their mug for defining characteristics — the distance between your eyes, for example. Once the device is confident it’s you, it unlocks and allows you to access the operating system.