Not in the App Store yet.
It's being used every day by the person building it, before anyone else is asked to rely on it.
The link that keeps working
This address is permanent. When the app is listed, opening it will take you straight to the App Store — so a link written on a card or left in a comment keeps working.
There's nothing to sign up for in the meantime — no waitlist, and nothing here asks for your email.