Just want to say, I think what can differentiate this from other browsers + extensions will come down to how well-integrated all of it is. Tab fatigue for work browsers is real and if this helps solve that, then it's worth it. From what I see on your landing page, the UX / workflow looks extremely attractive.
Couple of things,
a) I do think the $15 per month is a bit too high for my use case - this is the same price as Intellij - which provides enormous value (edit: over alternatives). b) there does not appear to be any dev tooling at least on your landing page.
Both of those together probably means I'm not going to use it, but hope you find your niche market. Good luck!