I access the NUC using VNC on Windows 10. I am just concerned that the BIOS update will leave the NUC in a state where it is waiting for some input and I won't be able to see it and get back in because Windows can't reboot. Note: I have the current BIOS option set to start-up on the application of power, if that helps.
Yes, you should be able to run the Express BIOS Update (EBU) executable and initiate the BIOS update from within Windows. Once the reboot is initiated, there is no need for input until Windows restarts after the operation.