Some vehicles with rain sensor can have SHD function for closing the sunroof when it rains, it can be with a custom i-bus module to when the alarm is armed, it would send a signal to the sunroof module to close the sunroof.

in addition to the i-bus coding you would need to keep the sunroof module alive with KLR and to close the sunroof and when it has finished to release KLR and to rearm the interior motion sensor.