I never used rclone, but I can tell you that a borg repository basically is a number of encrypted blobs of up to 500 MB size that are never going to be modified

I never used rclone, but I can tell you that a borg repository basically is a number of encrypted blobs of up to 500 MB size that are never going to be modified again (only created and deleted) + a few small metadata files. It rsyncs quite well.