Another thing @gruber perhaps doesn't consider is that Mastodon isn't the only Fediverse platform that's growing.
Pixelfed more than doubled it's userbase during the past year.
* Feb 2022: 73,100 users
* Feb 2023: 153,486 users
This is despite the fact that there was no Instagram migration!
So why are so many mobile devs just ignoring Pixelfed?