A new role in ARIA called "comment" is intended to help support ARIA annotations. The ARIA spec PR for it is https://github.com/w3c/aria/pull/1135. It should automatically compute its level, setsize and posinset when not provided. The level is based on counting comment ancestors until the root. Note: it is currently implemented in Chrome behind the flag --enable-features=AccessibilityExposeARIAAnnotations
<rdar://problem/58577502>
Aaron requested public comment. I can confirm that Apple Accessibility Engineering has no concern with the ARIA Annotations proposal and intends to implement the comment role. I can't promise a specific date though.
https://github.com/w3c/aria/issues/1885