The latest leak on the matter reveals that Samsung's Always-On Display (AOD) will also see some updates and new features in Samsung Experience 10. A hands-on video with the Android 9.0 Pie beta for the Samsung Galaxy Note 9 showcases a much more colorful AOD than what we're used to on Samsung phones. The current AOD on Galaxy phones can display notifications in the form of solid white app icons against a black background. This is going to change in Android Pie, however, as the update apparently allows for colorful notification icons on the Always-On Display. By the looks of it, the notifications will automatically grab the main color from the app's icon.
Another change is how the battery percentage, time, and notification icons aren’t in the center of the display anymore, but are instead aligned to the left. There also seems to be a change in the font used on the Always-On Display.