Fractional scaling in GNOME + Wayland above 200%

I've successfully enabled fractional scaling on my GNOME 3.38 + Wayland in Arch as stated here: https://wiki.archlinux.org/index.php/HiDPI#Wayland However, in gnome control center it now only shows 100% 125% 150% 175% and 200% whereas for my screen the best setup would be 250% (that I can set in Windows 10 for example). How can enable values above 200% in gnome control center or either set it manually?