Is there a way to do this ? I don't use iCloud for anything and would rather sync to backblaze b2 with rclone...
Doubtful on a iphone. I do this on Android though to google drive.
There is no real usable rclone on iOS but you have options outside of rclone to upload to B2 or just about anything else.
If you wanted rclone encryption, you can rent a VPS and do an rclone serve sftp or WebDAV and use a 3rd party program to upload to that which will then be passed to B2
What third party software? Is it open source?
I can host a sftp server with rclone no issues, but yeah I do need rclone encryption