It's basically Arch and a fully customized ready to go Hyprland setup (which is a fully customizable/programmable DE running on top of Wayland).

I would recommend just installing Arch, Hyprland and customize what you need yourselves so you aren't stuck using DHHs preferences.

Bonus: Along the way you will also figure out how he did it, like creating your very own application launcher with some scripting and https://github.com/abenz1267/walker

(I am in the process of exactly doing that)