Just in time for the launch of the Pixel 4 and Pixel 4 XL, Google debuted a new Pixel Live Wallpaper app that's currently only available for those two handsets. These "live" wallpapers respond with parallax and motion effects when you touch or orient the phone differently. And this app is meant to control these, or perhaps be used as a way for Google to deliver updates to existing wallpapers, or even introduce new ones without having to wait for the monthly Android update. Support for older Pixels could come (and we sort of expect it to), but for now, only the Pixel 4 and 4 XL have access to the app.
Source: Android Police