at least on the iMac it doesn't work, tried: ioreg -l -f | grep nits which should list properties of all objects, and the display I could find: ioreg -r

at least on the iMac it doesn't work, tried: ioreg -l -f | grep nits which should list properties of all objects, and the display I could find: ioreg -r -c AppleBacklightDisplay