I also have this same question. Any update on this Esri?
Specifically, if I have an image, pdf, or spreadsheet to link to from a Dashboard or StoryMap. If that item is shared with my organization, how can I insert the item as a rest url to link directly to the document. Not to the item details page. That is just confusing for users.
From what I've seen the item has to be shared publicly (which is not an option for my organization and I would assume for others) in order to have the rest url at the bottom right of the item details page. If that is available, then this wouldn't be an issue.
Anyone else have suggestions?