GNU Pass is a great example of Unix-y interoperability for me. I sync the .password-store folder over to my phone with Syncthing, where the Password Store android app reads it. Password Store in turn talks to OpenKeychain for my encryption key with biometrics support. Changes are also synced back to my other devices. Each piece of the puzzle can focus on doing one thing and doing it well, even on Android!
Password store for android: https://f-droid.org/packages/dev.msfjarvis.aps/ Openkeychain: https://f-droid.org/packages/org.sufficientlysecure.keychain...