So here is the update:
- Booted it from MediCat USB as CvH suggested (btw. this is really amazing tool, but I did not use "official" installer as my Windows raised security threats). Anyways I booted into its "mini Win 10" but these Intel tools showed exactly the same errors.
- So I gave up with the attempt to update it via usb stick. I found unused M.2 SSD in my drawer, I will replace it in the NUC and go regular way - install Win 10 and run updaters.