How did you managed to change it locally in darktable? I'm interested to add my Nikon D5600 until they add it officially.
<camera> <maker>Nikon Corporation</maker> <maker lang="en">Nikon</maker> <model>Nikon D5600</model> <model lang="en">D5600</model> <mount>Nikon F AF</mount> <cropfactor>1.534</cropfactor> </camera>