Hello! Sorry - at some point my notifications got turned off for the site without my realizing. Sorry for the delay. You should look into
https://web.hypothes.is/. It's made by the same people as genius I believe, and you can run it as an extension into your browser to annotate any webpage. The only trick is that the underlying structure of the page can't change or else the links to the annotations will break. I haven't tested it on Prism, but _think_ that it should work to activate a Prism page for use with
hypothes.is. The underlying HTML of the page shouldn't change once you make the Prism IIRC. The changes in highlights from various users shouldn't interfere with
hypothes.is unless I'm mistaken. So you could combine the two tools to get at what you're suggesting.