Individual external Webdav storage?

I was wondering if it is somehow possible to setup individual external WebDav storage for each user… i.e. use the external storage plug-in with a stand-alone Sabre-Dav server on a different computer. Then authenticate this Sabre-Dav against the main Nextcloud User DB so that each user can have his or her own folder on the external Sabre-Dav server automatically mounted in their nextcloud.

It sounded simple at first… but after looking a bit into this, it turns out that something like that is not that easy to achieve?

Thanks for any hints!