So I've ranted about this in various places on the internet...
Some recent HN comments of mine:
https://news.ycombinator.com/item?id=34855750
https://news.ycombinator.com/item?id=33541173
I am 100% down for building this, open source, if I had a team to help me see it through as it's just too much for one person.
Do you have any dev experience / interest in helping create such a thing?
How much work would it be to convert either Firefox / Chromium / Nyxt into this instead of starting from scratch?
I love projects like nyxt and respect their priorities, but without big-player extension support it's usually a no-go for me. Still, I'll be interested to see the ideas they develop trickle out into the rest of the power-browser ecosystem. I especially like that lossless tree history – history management is a very under-explored UX area IMO