Basically, they're using a custom auto-tiling desktop called Hyprland. When you install it, all you get is a wallpaper and a terminal app. Hyprland is mostly known for having fancy and customizable (if you know what you're doing) animations, so it looks even prettier in motion.
nice! i've been toying with the idea of dual booting for a while so i'm thinking i'll make it a weekend project. yes, i'm doing this primarily for the aesthetic lol
distros themselves don't look like anything, it's the desktop environment / window manager that you see, this is a wm called hyprland and you use mostly .conf files to change the look, but some things like the bar at the top (waybar) use css