Can confirm the Western Digital SN520 256GB NVMe drive is compatible with the Deck : r/SteamDeck
Gigabyte NVMe SSD 256GB vs Western Digital PC SN520 M.2 2230 512GB: What is the difference?
CompuCare :: WD PC SN520 256GB NVMe SSD
SDAPNUW-256G-1006 - Western Digital SN520 256GB Triple-Level Cell PCI Express NVMe 3.0 x2 M.2 2280 Solid State Drive
Amazon.com: Western Digital PC SN520 128GB PCIe NVMe M.2 SSD Internal Solid State Drive OEM Package : Electronics
SanDisk PC SN520 256GB m.2 2242 PCIe Internal Solid State Drive SDAPMUW256G OEM - Walmart.com
Western Digital SDAPMUW-512G 512GB PC SN520 PCIe Gen3 x 2 NVMe V1.3 M.2 2242 Internal Solid State Drive - Walmart.ca
Western Digital PC SN520 SDAPTUW-512G-1012 DP/N 0FFD82 512GB M.2 2230 NVMe SSD Solid State Drive
Used - Like New: SDAPNUW-256G-1004_UA Western Digital PC SN520 256GB M.2 2280 Pcie 3.0 X2 Nvme SSD SDAPNUW-256G-1004 M.2 SSD / Solid State Drive - Newegg.com
Amazon.com: Western Digital SN520 SDAPNUW-128G-1006 128GB PCIe 3.0 NVMe TLC 3D NAND M.2 Solid State Drive : Electronics