M.2 and OS/2
The M.2 is just a form factor port for different kinds of computer interfaces. The implementation of the interface will depend on the hardware. There are mainboards that support M.2 for SATA, other for NVMe (PCI express, PCIe) and some other support both.
SATA
There are reports of having a M.2 SATA SDD drives working on OS/2 Warp and ArcaOS.
Please remember that not all M.2 NVMe ports have SATA compatibility.
- WD Blue M2 2280 1TB SATA SSD
NVMe
NVMe is currently not supported on OS/2 or ArcaOS (2019-05-24). Some intentions of developing a driver from Arca Noae had been showed at Warpstock Europe 2019, but there is no driver produced yet. It is not even listed as an speculative project on the Arca Noae Roadmap page [1].
Some M.2 NVMe have SATA compatibility, so an M.2 SATA card can be connected and will work, but it is common.
Read more about NVMe at Wikipedia.