Pop Memory

I was looking thru the BOM, and was wondering how easy it is to get
the POP memory.
I love the concept of having the NAND and the DRAM in one device, but
worry about the
supply issues it creates.

You should contact Micron for access to the POP memory. There are no supply issues outside of what you can normally see in the siliconn world with lead times. These devices are readily available.