There is a Brave browser.
A case can be made that many of the browsers split from webkit (or split from things that split from webkit) long enough ago that there is competition, but IMO that's a far cry from a fully independent solution.
there's probably software already out there that does this same thing and probably does it better, id be hesitant to open-source what i have without a lot of cleanup and security changes.
so certain tab container groups go out certain proxies which in turn egress specific vpn tunnels