Access via WebDAV works for the medialib and resource-view. However, for the content-view only folders are visible, but not the actual content.
Adapt or reimplement a !ebDav Content View for your specific use case and content structure.
The WebDav Content View is an example that shows how you can implement such a view for your own project (resp. content structure). It's expected to work for playground and designground content only. It depends on strong structure of the content. Therefore, the WebDav Content View is in /apps/WebDav and not in /libs/WebDav.
Therefore, it's possible and expected that you don't see any files in content trees different from playground or designground.