Mozilla is nothing like Xerox, if anything Google is the new Xerox: they have way too much money so they throw it at R&D side projects without a business plan.

The big one for Google is transformer models, they basically invented LLMs only to play catchup with OpenAI later.

Mozilla successes have always been focused on the web browser, from the very beginning. Even the name reflects that: "Mozilla" stands for "Mosaic killer", Mosaic was the leading web browser at the time. They beat Mosaic with Netscape, they beat IE with Firefox, beating Chrome was their mission, and Rust and Servo were their weapons. It is sad that they dropped the ball.

Like Xerox (and Google), Mozilla tried doing some side projects, but unlike Xerox, they didn't have money to burn from their quasi-monopolies, and I can't think of anything particularly innovative coming from Mozilla that isn't a browser. I don't consider Rust to be a side project, it is a programming language for writing a browser, that it is useful for projects other than a web browser is a happy side effect.