I bought this NUC9 in Sept. 2022, which is years after its publishment, the BIOS version installed is 0044. I have installed ISS and was suggested to update the BIOS to version 0070. Several attempts were made through every method displayed in the very download page, and I didn't see any proof that indicates a successful update. Maybe you guys can have a clue about what should I do in this senario? I'm using Win11 Professional by the way.
Since it is such a big jump from BIOS 44 to the latest, I suggest that you update using the BIOS Recovery process. This is documented here: Intel NUC BIOS Update and Recovery Instructions. After you successfully complete the installation of the BIOS via BIOS Recovery, it is suggested that, to ensure that all firmware updates are completed, you repeat the installation of this same BIOS via the F7 method.