Listening to @shoptalkshow … websites in Safari in visionOS absolutely cannot tell what someone is looking at. Nope.
“Safari on Vision Pro will take such experiences to the next level, with a full stereoscopic view and environmental lighting — all in a privacy-preserving way. What or where the user is looking is never exposed to the web page.“
https://webkit.org/blog/14205/news-from-wwdc23-webkit-features-in-safari-17-beta/#spatial-web