Chromium can be forked. Minor browsers like Brave or Vivaldi do that, although they have to keep up with upstream, but they are shipping an ads-blocker that are blocking Google's search ads.
Note that Firefox or Safari aren't going after Google's business due to the search deal. At this point, Google is funding all 3 major browser engines, so they have a level of control going beyond just controlling Chromium.
Note that Firefox or Safari aren't going after Google's business due to the search deal. At this point, Google is funding all 3 major browser engines, so they have a level of control going beyond just controlling Chromium.