They need to be top level groups. But yes, if you have public repos repoa/repoa and repob/repob instead of user/repoa and user/repob, then my understanding is

They need to be top level groups. But yes, if you have public repos repoa/repoa and repob/repob instead of user/repoa and user/repob, then my understanding is both repoa and repob will hae 5GB each.