Very good topic !
I try more than one year to find a solution to unlock Z6 ProRes Raw without success.
I contact Simeon Pilgrim last year about video 1 (DIY add RAW) and he confirmed me that way it is inspire by his PTP Tool method. The hypothesis of HDMIRAW.KEY on card with specific code looks credible ( I read this info on two different forum). I try to reproduce the video 1 with PTP tools and 3.40 z6 firmware. But nothing is producing when I add the four lines on NikonDump / Program.cs . Maybe HDMIRAW.KEY is need...
Maybe Nikon will be inspire by Atomos for unlocking options remotely on theses old cameras in firmware....
It is very an old age to send the materiel to a nikon service center, with the risk, the price and the immobilisation of material. Finger crossing !