What all of these mini computers need is modular, high speed persistent storage. They all use SD, which is sooooo slow as to be unusable.

I've seen a few boards which take eMMc but they are few and far between, and require special (proprietary to the board) hardware to be installed on the eMMC chip.

Even still I'm not sure the bus would even provide much IO bandwidth. Storage is an area that needs a lot more improvement for mini computers.