The Pixel 2 and 2 XL include a number of small tweaks that other 8.0 devices, even the OG Pixels, don't have. For example, the home screen's theme changes based on your wallpaper. We already knew that was coming to more phones in 8.1, and there's another theme feature from the Pixel 2 that's in 8.1 as well. Accent colors are pulled from your wallpaper for the notification and power menu shadows.

When you open the notifications or hit the power button to restart/power-off, the system draws a shadow overlay on the rest of the screen. If you do this while on the home screen, it's tinted with an accent color from your wallpaper. I've tested with a few different wallpapers, all of which produce varying shades. It works the same on the Pixel 2 and the Android 8.1 developer preview.

Importantly, this only happens when you're on the home screen (including the Google Feed). If you're in an app or even the settings, the shadow is the standard gray color. It's likely Google is using something similar to the Wallpaper API added in Android 8.1 on the Pixel 2's special 8.0 build. As we've come to realize, the Pixel 2 includes many features from 8.1.