SSD upgrade & 2 quick tips - Yes the SK Hynix BC501 does work with the Steam Deck. : r/SteamDeck
Amazon.com: Hynix HFM256GDJTNG BC501 256GB M.2 2280 PCI-Express 3.0 NVMe SSD Solid State Drive L15194-001 Compatible Replacement Spare Part for Sk Compatible and Other Systems : Electronics