It is expected that Substratum team are working on some sort of theme manager app for Android Oreo, which will be made available very soon. (phoneradar.com)
Thus, in order to get Always on Display working, we will be using the Substratum theme manager with its Andromeda plugin in order to install our special framework overlay on the Nexus 6P, Pixel, and Pixel XL. (xda-developers.com)
The most relevant features which will be added are: you will gain more speed, you will be able to download apps from outside the Google Play area, make backups easier, optimize and customize the looks and use the personalized theme manager (you will get a different interface from the one featured by default). (android.gs)