Yes and no : Kragnos is not really part of Kruleboyz release .
Yes , no tyranids showed up during Ark of omen campaign.
So I don't wait skaven release during Dawnbringers campaign while we have strong hints and rumors on Dok/Morai heg , Obr , Std , Khorne and Cities.
Apparently from book 3 we know that Drogrukh ( scions of Kragnos) are still alive ....👹