How to Play Sound Files on Client

While the Android app can’t do this, I think you can do so through your browser. Though you will need to have the browser open at the time you play the sound. See HowTo: Listen & Talk to your Home which I think will get you started.

Or you can use Tasker to poll OH Items periodically and play the sound when they change state.

Of course, Telegram/etc should work as well.