Is there any advantage enabling and using the IRST driver for my main NVME SSD drive (not RAID)? I guess I would have to enable IRST in the BIOS then select the option Map PCIE Storage Under VMD? There is also an option to Map SATA Controller Under VMD which I don't understand.
Currently, I am just running the Windows SATA drivers for my 2.5 " SATA drive. The Intel version might be useful if you wanted to try it, just don't let it install the Optane drivers if you don't have that. Would it provide an advantage over the Windows driver, I don't know.
The Intel drivers will install a Sata/PCIe premium driver that will run M.2 SATA drives and M.2 NVMe drives that are running in a SATA capable M.2 slot, if that configuration is being used.
As far as I know, the VMD driver you mention is not relevant.
As far as I know, IRST offers nothing if you are not going to use RAID or some other advanced feature provided by it. I wouldn't use it unless I had a specific need for it. It shouldn't improve performance over just using simple drives.
In the past (and possibly still now), it blocked SSD TRIM, if memory serves (so does the AMD RAID, last time I checked). That potentially harms long term performance and endurance for SSDs. I think Intel may have fixed it for single drives, but not certain about that. Modern SSD controllers can supposedly cope with not getting TRIMs, but it's better if the OS does send TRIM commands. That applies to both NVMe and SATA SSDs.