I am not sure if there is one for the XPro3 (yet) but a cage and grip combo I am particularly pleased with is the SmallRig one with an accessory wooden grip. While principally intended for video shooters, I understand, I handled one on a Sony 6000 and was blown away by its handling - the grip is big and hand-filling and the cage gives a feeling of solidity as well it might.
Quirky, but on the Sony at least I really like it. Many may not prefer something like this but it is surprisingly functional and looks kind of cool. The main issue could be that a cage might interfere with the downward flippy screen.