There are many products on the market that claim to convert M.2 NVMe SSDs into fast portable external storage. However, OWC claims that its own such housing is the first to come certified for Thunderbolt 3 speeds. Accordingly, it may achieve 1.533 gigabytes per second (GB/s) in "real-world performance".
https://www.notebookcheck.net/OWC-launches-the-Envoy-Express-the-world-s-first-Thunderbolt-3-certified-SSD-enclosure.478307.0.html