Considering there is currently no external siren for the home alarm, it would be incredibly useful to add an automation to enable the home alarm “sound the alarm” to trigger the floodlight alarm. Hey presto: external siren.
I think the problem would be that the floodlight doesn’t talk to the homebase and that’s where automations are linked. If they ever get the floodlights and indoor cams to talk to homebase, your idea would be simple to implement.
Would love to see this happen too, the siren on the homebase is woeful and can easily be unplugged. If we could have the floodlight going off too maybe even the lights flashing on and off as well it would make the system much better.