Amazon.com: Solid State Drive L18845-002 Compatible Replacement Spare Part for Western Digital PC SN520 SDAPNUW-256G 256GB M.2 2280 B+M NVME PCIE Gen3 x2 SSD : Electronics
Amazon.com: KingSpec 512GB M.2 NVMe SSD, 2242 PCIe Gen3x2 Internal Solid State Drive for Laptop/Notebook (2242, 512GB) : Electronics
I harvested a PCIe Gen3 x2 NVMe 1.3 SSD from my older laptop, the problem is that its length is short. I've held it in place with some tape, it should hold.
NGP80_NEW Western Digital PC SN520 SDAPTUW-256G 256GB M.2 2230 Nvme Pcie GEN3 X2 SSD NGP80 M.2 SSD / Solid State Drive - Newegg.com
HP 128GB M.2 2280 SN520 Pcie Gen3x2 - L18844-002
SKHynix 512GB 256GB PCIe Gen3 x 2 M.2 2242 NVMe SSD HFM512GDHTNG-8310A BA SSD | eBay
Amazon.com: PCIe Gen3 x2 USB 3.2/3.1 Card ASM3142- PCI Express to 4-Port Type C HUB Internal Expansion Card Controller Adapter PCI Express Card Desktop PC Support Multiple INs : Electronics