It's also worth saying: ActivityPub wouldn't have made it to W3C Recommendation without Mastodon's community. About 8 months or so ago, I was in despair because it seemed clear that we wouldn't have enough time to wrap up the work that needed to be done in time to make it through the process before the group's charter ran out. Mastodon's interest in AP directly lead to an extension and a renew of enthusiasm.
Thank you everyone. It means a lot to me.