I model the 40s and though plywood did exist long before then, it wasn't commercially used for such things as boarding up windows that I can tell form photos of the time.
But I have looked at plywood placed on structures and wondered how I'd model if it I had to. What I decided was if I was going to do so, I'd take a good photo of real plywood, print it in scale on photo film, then hit that with dullcoat and put it in place. I've done similar things with signs on a diorama I built for someone and people can't figure out how I did it as it's spot-on for the real thing (because, it is the real thing for the photo).