That's true for the Arduinos of the world. But you need very very high volume to make designing a PCB with a complex BGA like the Pi worth your while. The indus

That's true for the Arduinos of the world. But you need very very high volume to make designing a PCB with a complex BGA like the Pi worth your while. The industry standard is to use a system on module, and there are plenty of those from a long list of manufacturers. The Pi foundation has one too, what they call compute module.