Looks good! Mine seem to like a 1-2” lip on the inside wall of the nesting box. This can be added later of course.

I line the bottoms of chickenish things with a product called Poly Wall, it’s about 1/16th thick plastic with a very slight texture. Cleans easier than sheet vinyl, and is more durable and cheaper.

I would remove the screw for the roosting bar and mount the bar another way. When you put the siding on, it will capture the screw which makes replacement miserable. I’ve removed a lot of roosting bars.. they never seem right and chucking them is often better than cleaning them.