I think you’re right that the market for this is probably pretty small. But more so because these federated solutions won’t replicate the addictiveness and vitality of Twitter.

I think the big thing that’s missing when comparing people leaving Twitter to people who said they’d move to Canada is switching costs. Like it is a heavy lift to move countries, much less so to stop using one platform and start using another.

I deactivated and deleted Twitter last week and added it to my filter list in ublock. Most of the accounts I was following already have a Mastodon presence, though YMMV depending on your personal interests.