Their is a driver to get fans working or at least usable. github.com/0xGiddi/qnap8528

To build the driver you usually have to enable Dev mode on truenas scale. I did not want to this so I made a container which can build the driver for you. This way you do not need to enable Dev mode and their for remove the write protection on the host OS. github.com/kylian-002/Truenas-qnap8528-module