Valve Steam Deck has M.2 SSD slot but might not be easily upgradable
 

M.2 2230 SSDs are hard to find

According to Gabe Newell's response to Reddit Steam members, it appears that the Valve Steam Deck features an M.2 NVMe 2230 slot, making an upgrade possible, but Valve says it is not intended for end-user replacement, even if you can find it.

In a response to Reddit Steam community members, Valve's own Gabe Newell confirmed that Steam Deck console indeed uses an M.2 NVMe slot, but it is a 2230 form-factor one, which is pretty hard to find. In two separate emails, Newell confirmed that it is both M.2 2230 form-factor slot, even in the base $399 version which comes with 64GB eMMC storage, but official specifications from Valve say that these are "not intended for end-user replacement".

The M.2 2230 is a hard thing to find on the market, and most come as salvaged units from other devices. KIOXIA, a well-known manufacturer, has a few of these in retail, and in Europe, these can be found for around, €40 for the 128GB, €60 for the 256GB model, €100 for the 512GB one, and around €190 for the 1TB model.

https://fudzilla.com/news/gaming/532...ily-upgradable