Valve boss confirms the Steam Deck SSD is upgradable - Hardware - News - HEXUS.net
Looks like buying the 64GB version is the better value :: Steam Deck Discuții generale
My experience replacing the Steam Deck SSD | Logan Marchione
How To Upgrade The SSD For Your Steam Deck - 64GB to 512GB! - YouTube
Upgraded the 64gb to a 256gb, went pretty smooth and simple, only problem I ran into was removing the side clips of the decks casing, it just wouldn't budge. : r/SteamDeck
Steam Deck has M.2 2230 SSD slot, but Valve does not recommend upgrading it - VideoCardz.com