Android fundamentally still is a Linux system which have runlevels/targets intended for recovery purposes.
Is it possible to stop the Android OS far enough so that Apps, the UI and most system services aren't running anymore but I still have adb access?
initrunlevels or targets. Recovery is a complete operating system in itself, having its own kernel andinit. Related: How to quickly understand the Android UI.adbdis aninitservice which can run independent of the UI. But it can be tricky. – Irfan Latif May 27 '22 at 15:00