Fair, to entertain the thought though, it'd make little sense if it was COTS due to either a loss or razor thin margins due to low demand. However nobody is stopping a hardware integrator approaching Apple to use it, but it'd probably be stupid expensive and shrouded in secrecy as Apple would not want to cede full control of its deployment due to things like Secure Enclave.

I think it's less about what hardware integrators want more what Apple doesn't want. Apple tries to be as soup to nuts about their solution as possible, they don't want to piece that out to give some of the margin of the best pieces to a 3rd party trying to compete with them instead. Anything they could pay is just from revenue Apple could already target directly and keep all of to themselves.

Everything has a price though. If you offered half of Apple's market cap, I'm sure they'd be changing their tune. (Yes it is an exaggeration, but my point is that there are exceptions.)

The problem lies in that Apple already gets 100% of the profit from being vertically integrated today (so the offer would not only need to be large, but more than what one could reasonably hope to make in return). If it were just that Apple had a really good CPU then both Apple and the 3rd party(ies) would be able to come to the table with a net positive deal, but vertical integration makes it so only 1 party (Apple, in this case) can come out ahead until they are dethroned for other reasons completely.