The cross of Toulouse is most likely a reference both to the regional arms of Occitanie, and the Gard’s century-long sojourn under the protection of the counts of Toulouse. I’m not sure about the chief, but if we want to get geographically symbolic (which we already know is kind of a fallback for Louis), it could either represent the coast of the Mediterranean, or the foothills of the Cévennes mountain range. Personally, I’d favor the latter. Either way, points for making me go look up the distinction between engrailed and invecked again. (If you’re wondering, engrailed means the half-circles point outward from the charge - in this case, the chief - and invecked means the charge has the half-circles “cut out” of it.)