The problem is that Pie is just not a good name for the 9th generation of Android OS. In keeping with the naming convention, and maintain the letter 'P', a much better name is Potato.
People will argue that Potato is not a confectionery item, which is a convention Android keeps in when choosing their names. There is Oreo, Ice Cream and a bunch of other ones, all sweets or baked goods. However, you may consider the fact that not all pies are sweet, like Chicken Pot Pie.
Similarly, not all potato dishes are potato-like in their taste and consistency. Just look up Irish Potato Candy.
Besides, who doesn't like potatoes?