Additional alarm in uk, e.g. Dome siren

I use my ring alarm system to protect a garden studio, and would like some loud sound from within the studio to try to scare off an intruder. They won't hear the alarm going off in the house. I see that in the US you can get additional alarms called Dome sirens. When are these (or similar) going to be available in the UK. Or can you think of another way of doing this (apart from buying another external alarm). E.g. can Ring be programmed to trigger some 3rd party device via some kind of scripting, or ITTT or whatever?