> as long as they are ARM ISA compatible.

And apparently in Apple's case, they get to be a little bit incompatible (no nVHE mode, crazy custom ISA extensions, ...)

Which is also obvious proof that they're their own designs, because literally nobody else could or would implement the same Apple-proprietary ISA extensions. Here, we use some of the custom instructions in m1n1:

https://github.com/AsahiLinux/m1n1/blob/main/src/gxf_asm.S#L...

That won't work on any non-Apple core.