Couldn't you "just" wire the HDMI port to the panel control logic? That is, the HDMI-in doesn't connect to the computer part of the iMac, just to the display ci

Couldn't you "just" wire the HDMI port to the panel control logic? That is, the HDMI-in doesn't connect to the computer part of the iMac, just to the display circuitry. Edit: nevermind, I see you addressed this in another comment.