Someone just lets their dog shit while walking in the middle of the sidewalk and doesn’t clean it up. People are wild.

If there are dig holes in your yard it would suggest that whatever is doing the pooping is spending some hanging out. And since it’s right up close to your house I’m guessing it’s not a leashed dog. I would guess it’s some other creature like a cat or wild animal as people don’t really let dogs roam free like that.