There are a couple of ways to do TTS when a sensor triggers. Here’s how I do it.
For MP3, you can use a doorbell product as mentioned, or you can use a google home. This is how I do it using the Chromecast Integration (beta). That’s probably the least Expensive way since you can pickup a Google Mini for so little. Some say they have various issues with the Chromecast Integration (beta), so there’s Cast Web API, which I also use. If you don’t want google listening in, you can just turn the mute microphone mute switch on and just use it for TTS and/or MP3 files
