It's also still a phone chip, so I guess it actually isn't about speed over efficiency.
Google is trying that and it’s not working out so well.
Yes, but that says you can’t phone it in. Google’s senior managers are not sweating Pixel performance unless it will lead to a decline in ad revenues - contrast with AI where they very quickly realized that people asking ChatGPT questions would mean zero ad sales.
If you're referring to the Tensor SoCs, no they're not using custom ARM cores. They're using the reference Cortex codes from ARM because Tensor is pretty similar to the Exynos.