Having backyard chickens is a joy and you will be addicted.
Beautiful and spacious setup.
I have the similar metal enclosure like yours, but smaller in size.
The chain wire metal mesh on our enclosure is the same size as your if I am correct. This size is too big as we found out.
We got small birds, rats/mice entered through the mesh holes
In Qld, we have snake migration from around October to end of summer. The chain wire metal mesh hole is big enough for snake to come through.
We added 1 square cm size metal mesh on top of the original enclosure mesh. This stopped the little birds flew through the mesh holes into the enclosure.
The rat/mice can not enter through the mesh holes, but they entered through the gap between the roof cover and the side mental bars.