A noobee question.
Is it possible to
Create a virtual device (or using the physical power strip as described above) to then turn on a zwave siren.
Have a homekit automation which uses a security alarm (triggered via an Aqara hub that supports Matter) to trigger the virtual device and then the zwave siren?
Scenario:
I have ST hub with zwave sirens and are moving to Aqara hub with homekit. Would like to be able to trigger ST sirens via homekit alarm.
Apple home cannot see the smartthings virtual devices, so you can’t do it that way.
however, the good news is that it’s very easy to do it with a Meross device, or any other physical device which is visible to both smartthings and HomeKit at the same time.
Use an Apple Home automation have the HomeKit alarm turn on the Meross switch/power strip socket.
Have that Meross device coming on be the trigger in a SmartThings routine that then turns on year Z wave siren.
No custom code required, homebridge not required. You just need a physical device which is visible to both platforms simultaneously.
(and of course you need to do something to turn the physical device off again so it’s ready for the next time.)
I use this method myself quite often to communicate between smartthings and HomeKit. 
Thanks, will give it a go. Very useful and had been searching for an answer for some time.
As I understand it, I should add the Meross device to ST and it should appear on homekit. Is that correct?
Get the homekit version of the Meross plug and add it to both Homekit and ST.
Current deal on Amazon for 4 pack but they offer single or 2 pack if needed