The idea is that this current pinephone will be low end to force developers to optimize for low powered hardware.

Not really. It’s a nice side-effect, but it’s not the reason they made this phone low-end. It’s low-end because there really isn’t much hardware out there that can support a close-to mainline kernel and other requirements Pine64 has. They’ve chosen the A64 because it was already used in other products of them and their community was already working on mainlining it.