Been waiting for this feature for quite a long time. There are great sound effects on Apple Music including a classic car alarm sound and a burglar alarm that I linked. Here’s the guide on how to get it all set up that I wrote for iMore:
Even though the HomeKit ecosystem has grown over the past few years, a crucial piece of the security side of the platform has yet to materialize: alarm systems. Thankfully, iOS 13.2 on iOS and the HomePod now allows you to use Apple’s speaker (or other AirPlay 2 enabled speakers) in automations, giving us the ability to create our own DIY security systems. Here’s our guide on how to get it all set up.