I think Calckey/firefish, because of it history and characteristics, tends to have more themed instances. Many of the so called “general” instances, are multi-topic or multi-fandom themed instances rather than actual general purpose ones.
I think someone not used to these things would see ‘Coming Soon’ and just leave it as not launched yet.
It’s probably not launched yet. The main instance hasn’t open (or rather moved from calckey) and other intances are moving from either old Calckey or foundkey.
Firefish has already set up a new site and infrastructure under their new name. The flagship instance of Calckey.social is in the process of moving over to Firefish.social. The migration effort is intended to retain users, posts, credentials, and data. The move is expected to officially happen over the course of the next few days.
I would say to wait at least a week to check the official instance.