Valves’ approach to the Steam Deck has been pretty similar to a PC. While it will have a set structure as released by them, almost everything about it can be replaced and customized. This not only includes the SteamOS, which currently has issues with Anti-Cheating Software but the inner workings as well.
On July 18th, PC Gamer noted that a Reddit user had reached out to Valves’ Gabe Newell about the SSD that the Steam Deck comes with. Newell apparently replied to this person, stating that the SSD is connected to the handheld itself via a 2230 M.2 slot, which means that in theory users can even remove and replace it.
While this prospect might be exciting to some, it seems that in some cases with the system, just because you can does not mean you should. The official Steam Deck website was updated to ask users to please not change out the SSD in the system. The storage section listed on the website states that it is “not intended for end-user replacement,” making it pretty clear that it is not intended to be replaced, regardless of if it can be.
This should hopefully save you the time of attempting to replace it. Since this is connected through a 2230 M.2 slot, most likely the user will have to disassemble the system in order to replace it anyway. On top of the time it will take to do so, this will almost definitely void any warranty the system has. This is most likely the primary reason the website lists that users should not do this.
However, this will undoubtedly not be enough to dissuade tech-savvy adopters of the Handheld who will flood youtube with how-tos and videos of how it runs.