Linux has full time developers. Blender has full time developers. Lots of other projects have full time developers. They still don't sell my data to Google.
A web browser is a very visible piece of software, relied upon by end users, businesses and governments alike. I'm sure enough people and organizations would donate their time and money to fund this, if it existed.
I edited my comment on your other reply and by my estimation, calculating every SHA256 of all MACs ever potentially issued takes less than 89 seconds on an RTX 3090.
I also think MACs are (or should be considered) personally identifiable information, since there is potentially a paper trail back to the person who bought it. Plus MACs are not secret information, it's broadcast on the LAN and for wireless modules over the air in the immediate vicinity (though some systems will randomize wireless MACs for privacy reasons). Privacy-unfriendly software has been known to collect MACs (even from other devices on the network and in the vicinity), so there are already databases connecting MAC addresses with other data.