Mozilla isn't a surveillance capitalist because it's not a capitalist at all.
Google banned AGPL-licensed software because they want to tie fancy frontends with surveillance backends.
Mozilla, on the other hand, made everything free software.
Firefox is very important because according to its user base it gets to decide, or not, on which standards get implemented by the w3c.
This is part of why Google Chrome was built, in my opinion.
To give a concrete example: if Firefox had 90% of browser market shares, there wouldn't be DRMs in Netflix.
Since the Electrolysis project, Firefox is private by design, secure, fast, and it has a great UI.
Do you want more privacy? Check your browser add-ons and your Twitter/Mastodon authorized apps.
Do you want a faster browser? Stop using Windows because it's kernel is a pile of garbage. Ubuntu runs the Linux kernel, so go use it: https://ubuntu.com.
Also: do you want to fork Firefox? Go ahead. Fork it. Just make sure you raise enough funds because you'll have to maintain a corner stone of the Internet.
You'll have to pay a fuckton of people. Go ahead. Don't sell anonymous data to marketing companies (and people give anonymous data to marketing companies since forever and it's not a problem). Just magically get enough donations to pay all this people.
The social network of the future: No ads, no corporate surveillance, ethical design, and decentralization! Own your data with Mastodon!