Why can't Gnome Software work with Arch repositories?

[pebcak]

Have a look at the following post on how you can use Gnome Sofware on Arch (-based) system and why you perhaps wouldn’t want to:

Is gnome-software working?

Please see these two posts for what you need to get gnome-software working and also for why you probably shouldn’t and what you can use instead if you really need a package manager with GUI: