You won't be able to use Wi-Fi until you install OS and then install driver for Wi-Fi card. But you can update BIOS right now from USB stick using F7 method
Here you can find the different methods you can use to perform a BIOS update in a NUC: BIOS Update Instructions for Boards and Kits
In this case, you can download the files needed in another PC and then use a USB stick as previously advised.
If you require any further information, do not hesitate to contact us back.