There should be a way to add an image to the competitor report, and the mock-ups embedded in the editing window seem like they're intended to do this. However, once you get out of the editing window, the uploaded image is not visible anywhere. This seems like a flaw.
Thank you for sharing this idea. It is possible to add mockups to competitor pages by inserting them as an image (see attached). Please let us know at firstname.lastname@example.org if we can help you with this.