After benchmarking 2 NVMe SSDs on the PRIME H670-PLUS D4, I wanted to boot from that drive/volume. The 2 main problems installing Windows 10 Pro onto the RAID0 volume were:
Windows installer couldn't see the RAID0 volume.
UEFI needs an EFI partition (100MB).
The first problem was solved by including the Intel RST drivers in a folder on the USB drive being used to install windows. (See this tool for instructions creating a setup/install USB drive). During install press F6 to load drivers, browse to the folder with the Intel RST drivers and choose one (it doesn't seem to matter which one). The second problem was solved by shrinking the volume in diskmgmt.msc (by 100MB exactly). Then using bcdedit to create EFI partition (see here for instructions).