Earlier quoted context omitted.
There's ungoogled chromium for that. Also doing that doesn't solve the standards problem we currently have. Google is able to push through any "standard". And those standards "unwittingly" help them maintain their search/ad dominance or prevent competitors. For example see manifest v3 or FloC (a.k.a Topics API). Once they gain enough traction and become indispensible, you either implement them or risk losing users.
But why would this change with a new browser written from scratch?
https://gs.statcounter.com/browser-market-share
which means Google has significant control over web standards