Does this smoke detector/siren works with SmartThings Hub V3 in Europe?
Yes it should work fine with the EU hub. It won’t support advanced features out of the box but the basic stuff should work just fine.
Do you think I can use both the siren and the smoke detector?
No it will need a custom DTH to use both. If you’re using RBoy apps you can send our support desk a request to develop one and we can look into it if you’ve purchased it.
I am not using RBoy Apps.