Is there any ebook/.epub or comic book (.cbr, etc)

... libraries/scripts/active-x controls etc that can be used to display those file formats in the Opus viewer panel?

I've searched here but have only found old threads re: this.
If it's not natively supported... will it be some day?
Has anyone found any solution to make this work in the viewer panel?

Any preview handler for those formats which works in File Explorer, Outlook, etc. should also work in Opus.

Support to treat .cbr as archives and enter them is built-in, and you can then view the files within as thumbnails and in the viewer. For a more fancy comic book reader, I'd look for preview handler options, but there isn't anything Opus-specific unless someone writes one.