> CHERI requires a lot of heavy lifting at the compile-and-link layer that restricts application code behaviors, and an enormous change to the microarchitecture.

Well, Apple already routinely forces developers to recompile their applications so if Apple wants to introduce something needing a compiler / toolchain update they can do that easily. And they also control the entire SoC from start to finish and unlike pretty much everyone else also hold an ARM Architecture License so they can go and change whatever they want in the hardware side as well.