I would imagine they could split their orders between different fabricators; they can put in orders for the most cutting edge chips for the latest Macs and iPhones at TSMC and go elsewhere for less cutting edge chips?

presumably they already do that (since non cutting edge chip fab is likely to be more competitive and less expensive) so, given they are already doing that, this problem refers to the cutting edge allocations which are getting scare as exemplified at least by Nvidia's growth