In reply to Weston Ruter.

Inserting external media via the media library was always a bad UX. not sure how you can even edit it after the first selection.

Actually forcing people to open the media library at all is not great... you can probably do the widget from as a drag target to images to make it slightly easier.

But generally I am with Nick below.... A media is just a form of content and if there is a need to be able to add general content to the sidebar, than a full dedicated post type and editing experience is more useful than handling it on one by one base (different for general text, different for images, probably different for audio, video, pdf, svg, ads ...). And post type will have the additional benefit for status and revisions and capabilities....