He has it because he is in our slack groups (maintained by @jimz011 and @dwains).
Joining our slack group gives you the ability to test themes like this early (as well as my own theme Homekit Infused).
But I’m not here to talk about my theme. I am here to tell you to test his theme, it is really great. It is imho one of the best themes out there right now (that contains not just the standard HA cards). I had the chance to test it myself as well and it works pretty great.
And most of all, join our slack group, because it is really awesome! Find the links on each of our repos and remember, respect is everything!
Keep posting in here so that people get notified about this theme!