So, I logged into Twitter yesterday for the first time in a few weeks to add my ActivityPub address to my profile.
I saw three trends in my timeline:
"Follow my Substack" (mostly journalists)
"I'm on Mastodon now" (tech, science, politics, some social media personalities)
"I'm staying till the bitter end" (comedy, celebrities, show business)
I don't follow brands or bots, so all humans.
I think there's a real opportunity for Substack to implement AP and join up the networks.