If something like KDE can build a whole desktop on a shoestring budget with some donations, Firefox can too. And I'd gladly donate to it. Problem is I can't because you can only donate to the foundation. And I don't want to fund their dogood distractions, just firefox.
Besides, the search deal will end one way or another. Either Firefox will lose so much marketshare that Google no longer bothers, or the DoJ will finally ban the search deals. Relying on it is ultra stupid.
Back of the envelope math says that's worth 50-70 million dollars a year, taking into account inflation. A cracked developer is worth 1/2 a million per year, both of Mozilla's core offerings are OSS so benefit from free code contributions. Is that not enough for a dozen highly paid software engineers, a well paid CEO and infra? This is ignoring future donations.
It sounds like you haven't looked into Mozilla Foundation's history regarding CEO salary, bonuses and overall use of funds.
also, I don't think a dozen devs is enough to support a competitive browser
anyway, companies are far(!) from just devs
Of course this funding would come with some pretty big strings attached. Including perhaps "no AI in the core system."