Since we do consider Embedded content part of the outline of a document, we also can make sure this content looks the same as the actual content in the document. The difference is that we could use this annotation space to add the embed metadata
You can see in the image above that the actual content does not have any difference from the document's content, but we render a colored line on the right that expands to all the embedded content, and the document title + other metadata on the side annotation section.