Games Played in the Steam Deck Reveal Were All Stored on SD Card (News ) - PCMag AU

It turns out that isn't an issue, with Yang revealing in a reply tweet that all the games played in IGN's reveal video were running off an SD card.

So all of the footage of the Steam Deck running games so far, be that Control, Portal 2, Death Stranding, Factorio, or Hades, has been from an SD card and not the internal eMMC or NVMe SSD drives.

We haven't seen a full game load yet, so it may be noticeably slower on SD card, but that really comes down to your choice of card.