I has a recorrent nightmares (* just kidding ) with something bad occurs to my nas (like a power surge due to strike) and i lost all my files. But is really hard to sync them with every cloud.
Odrive is a very good tool, and i will like to sync my owncloud personal cloud storage throught odrive to my dropbox, google drive and others supported.
Please note, though, that odrive cannot sync one link to another, so your original plan of trying to sync your OwnCloud/NextCloud to Dropbox or Google Drive wouldn’t work, at least directly. If you are hosting your own though, and have access to the underlying data, it would be possible to sync that data to cloud storage.