Painted 1/2" CDX plywood with vents.

Tongue and groove wood would look good and minimize waste. Can't tell from the pics if stained or painted would be best. Honestly with material prices and availability what they are right now, I would wait. I couldn't find any AC plywood the other day and what plywood I found was ridiculously expensive. If you go the plywood route, I'd use BC at a minimum. You'll be scrapping a lot with 3 foot overhangs. Maybe use the rough surface stuff with 8" striations to give a board look. It takes stain much better than smooth.

It also depends on how close you want to stay with the original design/style of the home.

Thanks . I was thinking of using azek product tongue and groove . but would probably be very expensive vs other options. House is near the ocean so exposed to alot of salty spray

If salt spray is a concern, you may wish to consider fiber-cement panels in lieu of plywood. If you're considering PVC in any form, just make sure you're sitting down when you get the price.