1. GNOME is the 800lb gorilla of linux DEs, so I would be surprised if it weren't the most common DE on any distro that doesn't default to something else.

2. I didn't mean to imply that Hyperland is driven by NixOS (NixOS is niche enough I doubt it drives anything); just that it seems to have hype on NixOS. I use NixOS, I'm semi-active in the NixOS community, and I regularly interact with NixOS users. I don't regularly interact with anybody that uses Arch, so why would I comment on the Arch community?