This is a set of NAND chips on a PCB, nothing special. They directly attach to the NAND controller on the SoC, which means as long as you stay within the capabilities of the controller, you could use other chips.

Third party boards have already been designed and made, and they work. The main issue is that people don't really know much about NAND, so they assume it's like an SSD (it's not) or eMMC (it's not) where you plug it in and some hardware magic turns it into a disk (it doesn't).

What happens here is that the secure enclave, cryptographic accelerator and flash controllers are all packaged together. This gives you sick speeds and performance while also making it more secure than your average OPAL TCG trash that often isn't even implemented at all.

To make the embedded flash controller work with the NAND, you need two things:

- NAND chips that actually work with the controller. Not all chips do, especially low-end crappy bulk NAND chips won't do. People keep track of the NAND chips that apple uses and you can buy those and it will be fine

- The data in the NAND needs to make sense (so either have it empty or populate it ahead of time)

- Using USB-C you tell the embedded controller to revive and it will setup the NAND for you, this is available to anyone (so not locked behind some secret sauce).

In a way, this is similar to having a classic SSD, replacing the NAND chips on that SSD, and then telling the SSD controller that it has new NAND chips. Or to having a really old MFM/RLL hard drive before IDE and SCSI existed.

The storage device really is just dumb storage and the smarts are all in the controller. While we have moved this around back and forth a few times over the years, there is no conclusive benefit to one or the other. Having more smarts on the device means there is also more problems/variability on the now 'smarter' device. This is especially problematic during data recovery, or when you want your data storage to be trustworthy.

A lot of the hardware work has been done by dosdude1, and a table of NAND chips like this one: https://forums.macrumors.com/threads/apple-silicon-soldered-... can show you some options.

The reason Apple does this is the same reason as ever: if they feel like this is the best way to make some sort of experience work, they will do it. And if they make fat stacks of cash in the process, they aren't going to be sad about it. This is something that isn't exclusive to Apple, but most manufacturers don't have to luxury to design their own hardware, they have to integrate with a lot of partners, use reference designs or maybe even outsource their hardware to some white label manufacturer. This is also why you see more glue, foam pads, smaller components etc all over the industry: it gets the manufactured devices to do the thing they want it to do. If PCs became modular in the process, that was a side-effect, not much of a goal. (The goal was to upsell crap later down the line so your market is bigger)

As for pricing, that is just whatever the market will bear and not all that much related to the cost of raw material. This is of course not new and is default practice in most commercial businesses. So cheap components does not equal cheap products. (but cheap components might equal low quality products in some cases)