We have had Woodpeckers drill quite large holes into the sides, the squirrels seem to leave them alone here.
I should think they will go like hot cakes when you find an outlet for them. Our local wildlife Trust has a man make boxes for them, he does it to keep busy, and lets the profits go to the Trust. he has even progressed onto bespoke Owl boxes and bat boxes as well. He has trouble keeping up with demand at times.
They look lovely boxes