I was too! I almost migrated to Vaultwarden, but I'm very thankful this fork is continuing the original maintainer's work.
APS moved away from OpenKeychain to PGPainless some time ago, from before this fork started. While not perfect either (see https://github.com/agrahn/Android-Password-Store/issues/287), PGPainless is being maintained, and from what I can tell from this APS fork's git log, is automatically bumped via their renovate bot (e.g. https://github.com/agrahn/Android-Password-Store/commit/9a6b596199d7eb87b40b53c4cb111ba7a5b48188)
Did you see the Documentation section in the README.md? You basically initialise a password store on your server, and you use an implementation like this to sync (SSH + git) your passwords, which are encrypted via your GPG key.https://www.passwordstore.org/ has some instructions how to initialise a password store on, for example, your server. Then refer to https://github.com/android-password-store/Android-Password-Store/wiki/First-time-setup to configure the app.
I was too! I almost migrated to Vaultwarden, but I'm very thankful this fork is continuing the original maintainer's work.