But like I said, I sincerely do hope Threads follows through on their plan to federate. But it's just not correct to claim that they already have.
Supporting one user end to end is a huge milestone and the first step in rolling it out to the other hundreds of millions of users. Especially when Threads isn't a standalone platform but is built on top of Instagram which means we could see it integrated with ActivityPub as well.
The fact that Meta cares about ActivityPub at all is a huge win for open, interoperable standards.
So launch in July 2023, handful of accounts have AP support in November-ish 2023, full AP support end of 2024? I guess it's not nothing, they did have to bolt something entirely new on top of IG's infrastructure. But for a team that big, feels like we'd be seeing more if it was a true priority for them. Plus Threads leaning towards opt-in AP support which will only inhibit uptake (that was the last I heard, anyway).
I'd be shocked if Instagram ever went with ActivityPub, though.