Honestly I may be getting old but I neither understand CachyOS nor Omarchy.
Just use archinstall and set up your arch how you want with it. I would usually install Gnome and some other DEs and then just start whichever one I currently feel like using from GDM. My dotfiles already handle all the Hyprland config and are way lighter than Omarchy.
I mean... I get wanting sane defaults but I feel like plain arch already provides that.