nobody actually needs HID for this. It would be nice of course, no driver messing and such, but if they provide a driver, that is enough for most people.

NFC can transmit arbitrary data in a way of bulk transmit. this is kind of like USB, which has a very strict protocol (which does NOT include device specifications such as HID, but doess include endpoints of communication and communicaton specs), and can transmit data via bulk. so, if there is a program at the device (== driver) which recognises the keyboard (e.g. by some kind of nfc id? i dunno, in USB world it is Vendor ID and Device ID), and somehow manages to read the communcation (probably via polling, as said), it will work with nfc only.

....would be interesting to use a "normal" nfc tag reader before installing the driver. i guess (!) that it would read another "tag" everytime you push a button on the keyboard.