Actually just discovered that OWC have the Envoy Ultra Thunderbolt 5 portable SSD in either 2TB or 4TB.
Trouble is they only have it with their own Aura drive modules rather than an enclosure-only option that you can fit your own M.2 module inside, which would make it cheaper and quite possibly faster (if Samsung’s 990 Pro NVMe M.2 stats can be believed for example). It’s also on 30 day preorder, and like the Sabrent, not exactly cheap.