I'm glad this point is continuing to get hammered home. Because on what feels like a nearly daily basis, I'm still seeing people surprised and learning for the first time that what they think of as a whole browser ecosystem is really just a bunch of things using a Chromium foundation.
But to try and be constructive for whoever's reading and thinking of their next AI browser, I would be impressed by a wholly alternative browser engine, or demonstrations of major capacity to maintain programming upkeep of alternatives on par with the programming capacity supporting Chromium. A big part of the Chromium "moat" as it exists right now is the ability to bring disproportionate resources to bear on browser engine modernization. I would be impressed if AI tools were being used to demonstrably close the gap, because it conceivably could have important implications for getting us away from the browser monopoly problem.