I think trying to do a “modern web browser” which is almost like a whole OS, is the wrong path to take. To retake the internet, we need to return to the basics. A simple web browser that does, at best, HTML and CSS. Heck, maybe even Gopher / Gemini support. No javascript, no worry about code execution, no “dynamics”. Much easier to develop and maintain, and promotes a leaner and safer internet.
Now, be it a hobby project or some sort of, by miraculous intervention, cleaned-up Mozilla, that I leave to the peoples.