Facing the same problem…
Indeed, the Webview element needs a url definition… Linking the Webview to a String containing the URL does not work…
I do feel that this should be changed …
For example, the Image element accepts a String item - Element Type ‘Image’:
item can refer to either an Image Item whose state is the raw data of the image, or a String Item whose state is an URL that points to an image. Some clients may not (yet) consider item.
Is there some where we we can request this?
On github maybe?