You said you were going to use the cloud services, so even if you self-host, using a cloud service api carries the same risk as using their apps. This is an app to unify all the remote storage things.

However, after looking at the code, I retract my comment and caution you not to use Drivebase:

[crypto]

Generate: openssl rand -base64 32

masterKeyBase64 = “<base64-encoded-32-byte-key>”

If this is a salt or a seed, the documentation is wrong. But it looks Luke they're using this base64 value as the actual key.

base64 values can be reversed very trivially.

Don't use this.