Any free pallets being given away locally?

Even a bare bones rectangular frame or lean to with a corrugated plastic sheet on top could work

Edit: Depending on budget and space there are also covered chicken coops that can have the doors left open. I had been looking at them to use as a catio

For portable options there’s a pvc pipe frame and a tarp https://au.pinterest.com/klevercages/chicken-coopsrun/