@corlock I've worked with Hypothesis add-on as well. I met their work in 2015 during our "Hack on MDN" event at Mozilla where I developed an annotation add-on for Firefox to help reviewers annotate MDN, people then pointed me to Hypothesis afterwards and I played a bit with their add-on.

I think this is a great project and if there is any way I can provide any form of help, don't hesitate to ping me, even if you just need more hands testing it out.

Also, if done with care, this add-on could work on Firefox and Chrome and even Edge from a single codebase.