I have a GPD WIN 2, it's awesome. They basically stuffed a M3 laptop into a handheld - thus the price. And the main storage is a user replaceable M.2 2242 SSD, the uSD slot is secondary storage.
You'd be surprised at the PC games it can play pretty well
And I wouldn't buy it from Amazon at that price, generally it sells for $700 for the 128GB model, still steep, but they did cram a lot into it. There is also a 256GB SSD model coming soon