I have been trying out the lates Android App on a Chromebook, and generally it works quite well.
However, for daily use it’s not really helpful, as it’s not integrated into the ChromeOS File Manager.
ChromeOS does offer certain deep integrations, for instance for VPN and File Systems.
Other Encryption apps like Boxcryptor support these kind of integrations.
See here for more information:
Unfortunately, i haven’t found the developer documentation on how to adapt the android app.
for the time being, using the ppa or AppImage works well enough. Although i have to share my local storage in the linux VM, decrypt and route the decrypted folder back to ChromeOS. Works, but it’s clunky.