We do have an open source browser, it dates back to 2002.
It's has higher desktop use than Linux - 15% of desktop browsers according to wikimedia compared with 7% for linux (about half of which is chromebooks)
Chromium? I'm dreaming of something without a giant corp behind it. A project that, at it's core, would always and forever, celebrate uBlock Origin, and things like it, instead of making up "security" issues to thwart it's power.