Github

r/pgp

r/fossdroid

It’s not unmaintained:

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. We will try to consider and merge contributions where possible.

Hopefully it’ll get forked soon. This is what I use to sign/check and encrypt/decrypt emails with K9. Best FOSS alternative on AOSP phones.