I use this when, say, browsing through the excellent XKCD web comic, since a good portion of the humor is hidden in the title text aka the tooltip you see when you hover over certain images.
(define-command-global copy-hint-image-title-text ()
"Prompt for image hints and save its title text to clipboard, if possible."
(nyxt/hint-mode:query-hints "Select image"
(lambda (results)
(alex:if-let ((title (plump:get-attribute (first results) "title")))
(trivial-clipboard:text title)
(echo "No title text in selected image!")))
:multi-selection-p nil
:selector "img"))