WARNING: This software is no longer actively developed. We will still apply security fixes where reported, and do basic maintenance work, but no new features or will be worked on.
I believe K9 still relies on this for key management, does anyone know if this is being looked at? Are there alternative key stores for Android that would work?
It’s not just K-9. Basically, any software doing PGP/GnuPG on Android uses it unless it has its own implementation (R2Mail2, FairEmail, …).
But note that that post is over a year old. It is still maintained, just not under active development. So you still get your sporadic security updates.
Nevertheless, the developer only has limited time and basically maintains everything himself (I had an opportunity to talk to him in person at a conference I Hawai’i a few year ago). – You could help him by donating or contributing.