The Substratum theme framework now supports system-wide themes which don't require root on any device running Android 8.0 Oreo. The developers behind the solution have started working on support for the latest major iteration of Google's mobile operating system as early as March, and the upcoming feature is meant to be the pinnacle of their latest efforts, allowing users to theme their operating system without rooting their devices. The achievement can largely be attributed to Sony’s Runtime Resource Overlay (RRO) that eventually grew into the Overlay Manager Service (OMS), a software solution which powers Substratum.
Sony's theme engine was accepted into the Android Open Source Project (AOSP) earlier this year, which immediately prompted speculation that system-wide themes will be compatible without rooting a device powered by Android 8.0 Oreo. Following months of development, that achievement is now a reality and any device with the newest build of the most popular operating system on the planet is now able to take advantage of custom themes without its owner having to root it and install a custom ROM. The functionality is only available on Android 8.0 Oreo and later versions of the OS seeing how it wasn't until this build that Google provided developers with full support for the OMS. Substratum themes which didn't require custom ROMs were technically already available on devices running Android O Developer Previews but enabling them required root access, at least until some developers didn't come up with a better solution.
The newly added ADB shell commands present in the code of Android 8.0 Oreo that can enable and disable overlays were found to be functional alternatives for activating Substratum themes and they don't require root access, XDA Developers discovered, noting how the solution still requires you to use a small PC application or an ADB shell command and is reversed once you perform a hard reboot of the system. Regardless, even a hard reboot doesn't delete the themes from the device and only requires you to re-enable their privileges. The process itself may still break some themes which were designed to work on rooted devices and modify particular settings like fonts, though the development is still significant in the sense that rootless system-wide themes are now finally available within the Android ecosystem. Refer to the source link below to find out how to take advantage of the latest breakthrough in Android development.