The way Linux kernel stuff works, is you do a Linux internship with GSoC or Outreachy or LKMP , and then core Linux contributing companies like Intel, AMD etc gobble you up. Or you join FOSS consultancies Like Igalia, Bootlin, Collabora etc. Or you go the rockstar Patreon way like Asahi folks, trading off money for independence.

https://lwn.net/Articles/997959/ https://github.com/fossjobs/fossjobs/wiki/resources

Igalia is probably the best option for getting into core browser/etc work, they are hiring for WebKit/Chromium and are also working on Servo.

https://www.igalia.com/jobs/open/