I used Firefox for roughly 19 years at least or a bit more. I switched to Edge and have been very happy for years now. I didn't know they committed to supporting V2 but it does appear they intend to as long as it serves user choice and privacy needs.
I left because they kept stripping features out that I was used to whether it was my RSS toolbar feeds or something else. I forgot which feature removal was the final straw, or if it was a bug or two that irked me. While I was never a Chrome user, I found Edge was an alternative that I was happy with. I also see a lot of benefit to native browsers. Ironically, that I learned about from Mozilla's own devblogs.
Supporting V2 like this is the exact opposite of what drove me away. I'm cruising so happily on Edge that I'm unsure if I'm willing to do another shift, but I am going to reconsider my life choices.