This works in the UK
Install Fireangel smoke alarms, heat alarms and co2 alarms throughout the property, also with every one of these devices, install the fireangel SmartRF W2-Module into it, get a WI-Safe2 gateway and link them all together in one big network.
Enable the alexa fireangel skill
Create a routine in Alexa when Ring alarm goes off, get her to test the fire alarms, and repeat every 10 secs
Every single alarm will start to shreik, all linked together - very very loud
Fireangel also do a linked external siren and relay which are both part of the SmartRF network too
Apparently, you can get a ZWave module for the alarms in the Netherlands, but not the uk