Are We Fission Yet?

Yes!

Fission (Site Isolation) is the Firefox project to implement process isolation per-site (eTLD+1). In a Fission world, a webpage serving multiple cross-site iframes will be rendered by multiple processes, while multiple tabs or iframes from the same site will share the same process.

Fission's rollout to the Firefox Release channel began in Firefox 94 (2021-11-02) and completed in Firefox 95 (2021-12-07).

You can learn more about Fission on the the wiki. The Fission team can be reached at the #fission room on chat.mozilla.org.