End of Life for Android 4.0-4.2 devices
NYFAQ (not yet frequently asked questions)
Q: when?
A: Most likely v2023.06 will be the last with 4.0-4.2 support.
Q: why?
A: Modern toolchain
Q: app x runs on Android y. Why this don't?
A: KOReader != app x
Q: Will be possible to backport new features to unsupported devices?
A: Nope. But if you backport something that's not trivial please keep us informed
Q: Will be possible to target non supported APIs building from source?
A: Nope, at least not easily. You'll need to revert each commit that relies on the new toolchain for each one of the libraries that KO uses, and there're a bunch of them. Things will become a mess after a while.