The 2230 M.2 SSD that Valve integrated within the Steam Deck can be accessed and even replaced with a larger capacity model. However, performing such an upgrade could shorten the device's life.
M.2 ssd slot RSS
Active cooling could become the norm for the upcoming PCIe Gen5 NVMe SSDs according to storage controller maker Phison. That may not be enough for long as next-gen connectors are also in works.
Sony is all set to release the big September update that will include support for the M.2 SSD slot, 3D audio through your TV's stereo speakers, and other UX features and customization options.