Doing a bit more digging on this. If I get something like the Thinka Z-Wave to HomeKit hub, could I use that as the controller to integrate the IQ Panel with HomeKit and then connect to Brilliant via HomeKit?
Searching these forums it looks like Quolsys might have removed secondary z-wave controller functionality from the IQ Panel but I am not sure if this is true or really what this means (have only ever used the IQ Panel as my controller and never tried to use different hubs, controllers, or interfaces before).