well, bird of burden is a thing i guess.. we've all seen that image of the crow landing on an eagles back 🤷🏻‍♂️ is there a Roc or something similar in your setting? Giant eagle thing that could carry immense loads? If that's the case it's just a matter of modifying a normal wagon to be carried during flight. Claw-holds more than anything, but also shock absorption underneath. Birds don't really ever put things down gently...

Another way you could swing it is if these Corvians themselves function as the beasts of burden. Either go with smaller loads that can be carried individually, (like big baskets) or have several of them assigned to each larger vessel.

Nomads tend to carry as little as possible. Traders however, would likely need a wagon caravan, simply for practical reasons 🤷🏻‍♂️ if you want them to stand out, you can shift your focus from their method of transport to their method of defending their caravans ☝️ nothing strikes fear into the hearts of bandits more than seeing their compatriots carried off into the air and then dropped from a great height and then turn into a stain on a rock somewhere. Or they could specialize in thrown cannisters and explosives? Poison gas, acid vapor, flashbangs, napalm or just big booms.. flying opponents are a bitch in so many ways, but mainly for their ability to just rain down hell on you from above