Some dude on Reddit claimed he had a Gen 3x2 drive and posted the model…
Transcend's industrial PCIe M.2 SSD MTE352T features 96-layer 3D NAND flash and an endurance rating of 3K P/E cycles for superior performance.
www.transcend-info.com
Transcend lists the CrystalDiskMark results as 1700MB/s read, 1000MB/s write. The Gen 3x4 Kingston drive I have is 2500MB/s read, 1200MB/s write. The read is kind of irrelevant since the Deck is probably CPU limited when it comes to game loading, as seen by there being little difference between Deck ssd and microSD card game load times. There is a difference in download and transfer from external USB-C ssd, but I don’t think that will manifest between the Gen 3x2 and Gen 3x4 drives since the write speeds are extremely close.
In practice, not many buyers would even know what the original spec was, and they won't care because it won't impact any performance in any game the Deck (the GPU in which is at best equivalent to roughly a GTX 1060) can run.
Deck is probably only half as powerful as a GTX 1060, maybe less. It’s pretty much spot on a stock RX 460 2GB, which is a little faster than Radeon 7850 oc.