combine
modifier.
https://rclone.org/combine/
You would need to configure your cloud providers using Rclone and then create single combine
config.
I haven't tried that myself, unfortunately we don't provide a guide how to set this up.
https://docs.s3drive.app/setup/providers/#setup
EDIT:
For Rclone configured back-ends we don't yet support thumbnails and media streaming (e.g. video playout). That will come eventually. (edited)