Samsung Now Mass Producing Industry's First PCI-Express SSD for Ultra-slim Notebook PCs – Samsung Global Newsroom
SEDNA PCI Express (PCIe) SATA III (6G) SSD Adapter with 1 SATA III Port (With Built In Power Circuit , no need SATA Power connector, best for Mac), SSD not included :
M.2 - Wikipedia
USB-C 3.2 Gen 2 to M.2 PCI Express SSD Enclosure - UPTab
StarTech.com PCIe 3.0 x8 to dual M.2 NVMe SSD controller card - Controller card StarTech.com on LDLC