Android 9 Pie is full of all sorts of changes, including the overview screen - which is commonly referred to as the multi-tasking screen. Google moved away from a vertical scrolling list of open apps, to a horizontal one, with large tiles and a row of commonly used apps at the bottom with the Google search bar as well. Many are not too happy with the changes here, but one of the bigger changes is that third-party launchers can now customize that Overview screen - with root access of course.
The guys that develop the Lawnchair Launcher, which is a popular Pixel Launcher alternative, were able to implement the new Android Pie Overview screen into the launcher. While the team doesn't want to share exactly how this was done, it did involve integrating the code for including the recent apps into their launcher. While Lawnchair Launcher has only implemented the Android Pie Overview screen, what this means is that launchers could include other ways of showing the Overview screen in their launchers. Whether that's going back to the Android Oreo way of doing things or another way altogether. Lawnchair doesn't want to share the code just yet, since this is still a work in progress for the launcher, and it wants to wait until it is more stable, to share how it was done.
Android has always been known for customization. As you can customize your home screen, your launcher, your keyboard, just about everything on your smartphone or tablet. But now it looks like Android Pie is going to open up even more customization for Android users. This could be a very cool thing, especially for those that might not be a fan of the new Overview screen in Android Pie right now. Though we will have to wait for other launchers to implement these changes.