The major road block when it comes to skeletons is motivation. One skeleton of average intelligence might be perfectly capable of baking a dozen pies. But would be only inclined to lie on the floor having an existential crisis in the wake of realizing it is a sentient skeleton. You’d need a tribe of skeletons, a culture. But it’s a fine line. Too many skeletons and they’d integrate into modern society, get jobs, make money, and buy pies instead of making their own. (Remember skeletons tend to be apathetic and will always choose the least labor intensive solution to a problem) On a similar note; too few skeletons would be seen as a novelty and would have no trouble asking for pies from skeleton enthusiasts. So, enough skeletons to be a nuisance to society and develop an independent community, and not enough to be normalized.
I think a safe estimate would be 600,000 skeletons in the United States, or 119 million worldwide. At that point, pie baking would be a symbolic gesture of cultural pride in the skeletons desire to be excepted by the world at large.
They might not bake exactly a dozen, but they’d bake at least a dozen.