Doesn’t seem possible to create custom AOV’s on hidden objects.
Simple example. You want to create camera noise, so you align a plane to the view and give it a white noise texture. Plug the white noise into an AOV output node, hide the plane from rendering, and hit render. I’d hope that the noise would still be rendered, but it doesnt appear possible.
I think the aov output node should always contribute to the AOV regardess of whether the object it’s on is visible in the render. Otherwise you have to use view layers and render more than once.