A flat steel grate with folding legs that stands over a fire, a fire pit or a bed of coals. It costs very little and is the missing piece between “we have a fire” and “we can cook on it”.
Its use here is specific. A charcoal barbecue is better for grilling directly, but a grate takes pans, which a barbecue grill often will not do stably. That means a fire can run a stew or boil water, and on a long stay that is real fuel saved against a gas canister.
Look for legs that are genuinely rigid when opened. The failure mode is a pan of something hot tipping, and a wobbly grate with a full pan on it is the most likely way to get burned in a camp kitchen.
Stainless or plain steel both work. Plain steel will rust and does not much matter; it is a grate.
Same rule as everything that burns: outdoors only, never in an awning or a porch, and not while it is cooling either. Carbon monoxide.