How hard would it be to "wrap" the browser in a ublock like shell, so that all network requests are filtered through a firewall before they even reach the chrome application layer.

It might be easier to maintain than an actual extension interface with hooks thought the code.

I don't think you'd need manifest V2 for such a rudimenty logic.

The reason why ublock origin is so powerful is because it works with the DOM/not at the network level and can use heuristics to determine wherever something is a advertisement or not.

I imaged you would use both.

I think you might be underestimating the scope of work that happens on chromium a tad, from Github's "pulse" feature:

"Excluding merges, 684 authors have pushed 3,139 commits to main and 3,866 commits to all branches. On main, 14,924 files have changed and there have been 740,516 additions and 172,682 deletions."

That's stats from last week. Last year Google apparently was responsible for about 95% of contributions. Other than Microsoft (which has the same bad incentives as Google) none of the alt-chromium browser companies has like, 5% of the engineers to maintain a real alternative

Yes, but as I said they can merge in changes. Apparently more than I thought, but still, they can.

Opera has pinch-zoom text-reflow in a chromium backend, and that seems to be substantial, and yet it is (on purpose) kept out of mainline chrome. So they do loads of tracking/merging too.

The scope of work to do a few small features on top of chrome wouldn't be a biggie, compared to the entire project.