It is ok to link something, but could you take a moment to add just a few lines to explain what your WTH is?
The WTH is that it is quite hard to do something as simple as that. That was my first use-case with Home Assistant and not a good start.
I don’t want/need to launch another add-on (like VLC) that would consume resources, potentially hang and in general be an overkill for this kind of task.
On a wider context: in my case HA automations are used in a house inhabited by elderly people. As you can imagine, they are not that digital and are not into apps/dashboards/notifications. The way to go to inform them about something is a plain USB speaker (I don’t want to replace batteries and/or have potential wireless transmission problems), playing back local sound files (potentially using TTS in the future).
Local playback is difficult to accomplish using something that would be associated with the web browser that the user is accessing home assistant with. While, for example, solutions like Browser Mod exist today, they require interactions with the page before you can target them as media players, due to limitations of how browsers accept auto-play of media.
If all you want is announcements, your best bet is to find a speaker that is powered by a squeeze-lite compatible media player. Those can be added to home assistant and then you can play back whatever you want to those speakers.