I too am looking for alternatives.
Official site: https://www.gnu.org/software/gnuzilla/
Binary build available here but not official:
https://icecatbrowser.org/index.html
edit:
I linked to a non-official site first, added the official site and made clear that the site offering binarys is non-official.
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
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.