Combi ovens are often good options, in part because of their versatility. When they're not being used to roast cocoa they can be used to roast nuts and bake brownies – and it’s often possible to make more selling your chocolate as brownies than as bars.
One of the best features of a combi oven is programmability. Once you dial in a roast you can hit that roast every time. You should also be able to program in temperature changes (start low then go high, start high then go low, or any combination).
Steam is great for a microbial kill step. Get the oven hot at the very beginning and inject steam to 100% humidity for 1 minute then get the humidity (and maybe the temperature) down as quickly as possible. One tip: scale the beans in to perforated sheet pans or better yet into air-fry baskets for better airflow. Consistent weight in each pan is key to consistent roasting, though you should be able to vary the number of pans without altering the roast.