I'm configured your gateway (C-8), as "helping" machine for my almost 80 years old family member. So far I have success on that, mounting different hardware, but this is not the main issue.
I recently bought "panic/sos button", which work perfectly fine (will be bound to siren in few following days), and I noticed, that there is option to which allow to use:
"Send, Speak, or Log a Message, Send HTTP request"
then there is
"Send/Speak a message"
I'm kindly suggesting new kind of action, called (this is just a temporary idea, name as you wish)
"Send/Speak a message and play (loud) alert"
So idea is to got on phone with hubitat aplication not only message, but played loud sound, to alert user, that family member needs urgent assistance.