I feel like those were somewhat easy to find (but not explicitly stated).
Lemmy.world for Lemmy
Kbin.social for Kbin
Mastodon.social for Mastodon
Once people are in there then we start talking up moving to and instance that fits their style. Kind of like picking a fighter character then picking a specialization at level 2. That's still a hard sell on Lemmy and Kbin where we don't have the account export/import/redirect tools that Mastodon has. I could see them coming pretty soon though.