If you're dead set on downgrading to an older version of Android, though, you could try installing a custom ROM. Custom ROMs come with improvements over the official software of your device, and developers sometimes keep older versions updated with security fixes. It's an alternative worth che...
We are already seeing somewhat of an uptake in Android Go from some custom ROM developers, such as by XDA Recognized DeveloperAdrianDC, with his work on LineageOS 15.1 with Android Go build configurations forseveral old Sony phones. The devices in question are the Sony Xperia SP, Sony Xperia ...