> If [an Apple] competitor could actually deliver better silicon than them, they'd be going to AMD, because AMD actually builds custom solutions and can be coaxed into at least getting decent security (see: Xbox), but that still leaves the power management gap on the table, and would force another ISA transition.
AMD has an ARM architectural license, they've released ARM processors (e.g., the Opteron A-series, the AMD Platform Security Processor, etc.), and were at one point experimenting with a common ARM/x86 platform (Project Skybridge).
If Apple wanted a third party to design an ARM-compatible processor for them, AMD would be capable of doing so. Indeed, when there was speculation last year about AMD developing an ARM processor, I suggested that Apple would be the only customer where that would make sense.[1] However, given the success of M1 and Apple's scaling strategy for it, it's unlikely that AMD has anything to offer right now that Apple would want.