But there are limitations. The studies were relatively small and conducted by the companies and researchers behind the devices. More long-term, independent research is needed. In addition, the studies on Duo and Lenire devices didn’t include a placebo-controlled group.
I don't typically see them with extensions. I can recommend a few if you want them, they work on mobile on both Chrome and Firefox. Not around PC ATM. Maybe it's worth making a bot that auto posts an archive.org link? Don't have time for a bit yet to do that but I know it's possible.