I never understood why people use unraid, mostly because I never understood the “parity” features, or honestly between you and me the lack of proper parity. But I have a Synology, so I can’t talk (price wise) and I have raid 5 everywhere so parity is a joke here too :p
Looks good to me.
The board has 4x m.2 slots apparently. So if you were willing you could get 2 extra nvme drives and use them as your cache instead. (Assuming the other 2 already purchased are for raid1 OS).
Have fun!