Amazon.com: KingSpec 1TB M.2 NVMe SSD, 2242 PCIe Gen3x2 Internal Solid State Drive for Laptop/Notebook (2242, 1TB) : Electronics
Amazon.com: LINKUP - NVMe Enclosure M.2 SSD to USB C 10Gbps Adapter | Aluminum Case USB 3.1 Gen 2 (10 Gbps) to PCIe Gen3 x2 Bridge Chip | for Windows & Mac
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.
SKHynix 512GB 256GB PCIe Gen3 x 2 M.2 2242 NVMe SSD HFM512GDHTNG-8310A BA SSD | eBay