With firmware version 2.0 on the Z9, Nikon introduced a new file format for video - .NEV (12-bit raw video). It seems RPD does not support this. I assume it’s just a case of adding the extension to a list of known extensions.
Note that I actually have no intention of using this file format (I was just testing if the free version of DaVinci Resolve supported this format on Linux - it does not), as the files produced are huge (my 512GB card will only record 11 minutes of footage), so this is just a heads-up in case other people are going to need it.