FWIW, Apple's been helping define CPU specs in-house since the 90s. They were part of an alliance with Motorola and IBM to make PowerPC, and bought a substantial part of ARM and did a joint venture to make Newton's CPU. And they've done a bunch of architecture jumps, from 6502 to 68k to PPC to Intel to A-series.

Folks who said CPUs weren't their core expertise (I assume back in 2010 or before, prior to A4) missed out on just how involved they've historically been, what it takes to get involved, the role of fabs and off the shelf IP to gradually build expertise, and what benefits were possible when building silicon and software toward common purpose.