The Pixel's "Flip to Shhh" feature is not groundbreaking, but useful. Third-party apps copy it to other phones because it's so convenient. However, it is not enabled by default and pretty hidden in the settings. To take full advantage of your pixel's features, you should learn how to use Flip to Shhh.
If you're not aware that Flip to Shhh will automatically put your Pixel on-screen, put it face down on a flat surface when you hang up the phone. This is of course intended for a protective cover that prevents the windscreen from touching anything. Therefore, Google may have decided to leave the setting turned off by default. But as long as you're not worried about scratches, there's no reason not to turn on .
Enabling Flip to Shhh
First, open the Settings app. Scroll down and tap System. On the System screen, tap Gestures.
At the bottom of this menu, the Invert To Shhh option appears. Tap on it and you will be taken to a new screen with an explanation of How To Reverse To Shhh. There will be a toggle switch. Tap to turn on "Mirror to Shhh".
If you now place your phone face down, you will hear a low buzzer indicating that the Do Not Disturb mode has been activated. With the exception of the rules that you have defined under Settings -> Sound -> Do Not Disturb, no calls, texts or notifications are put through.