I am installing on an Intel NUC8i7HVK i7-8809 with 2 Samsung 970 Pro 512GB M.2 NVMe PCIe x4 SSD. I would be using them for Raid 0 or Raid 1, haven't made my mind up yet on that. I will be using Windows 10 Pro 1809.
I have the same unit and have RAID 0 setup.
Head here and grab both the f6flpy-x64.zip (unzip this into a folder and stick in the root of the flash drive you will be installing from) and SetupRST.exe files.
Next head here and click 'PCIe (NVMe) RAID' to expand the directions.
Those instructions will show you how to both use BIOS to setup the RAID and how to use that f6flpy-x64 folder during the Windows install process to install the RAID drivers.
Once on your desktop install SetupRST.exe if you want to manage your RAID setup although this step is optional.