Apple has done that before. IIRC when the original iPod came out it used a new generation of HDD. Apple went to the drive manufacturer and said "we'll take all of them" and they agreed.

How is Amazon able to product their arm chips for aws? Assuming those are not the 5nm?

There's still 5nm silicon for sale, but just not at TSCM (the largest semiconductor manufacturer in the world). Companies like Samsung are just now getting around to mass-producing 5nm, and afaik there were a few domestic Chinese manufacturers who claimed to be on the node too.

As for Amazon specifically though, I've got no idea. They're a large enough company that they could buy out an entire fab or foundry if they wanted, AWS makes more than enough money to cover the costs.

Nitpick: it's TSMC, Taiwan Semiconductor Manufacturing Company.

Good catch, my mind always interprets it as Taiwan Semi-Conductor Manufacturer

Yeah, I always need to think twice before writing or saying their name. Same with ASML. I guess there is a reason why TLAs are much more common than FLAs.