I use chromecast devices and binding. The devices are cheap and super simple to add, they work, and its very simple to control each device, (even though the chromecast binding is/may acting up, and may cause other problems, just like Andrew mention above).
I use rules to send audio files to chromecast devices… Like my halloween prank audio file:
Item lydknap changed from OFF to ON
Halloween1.mp3 is located in the sound folder.
I also use GH devices in rules for text to speech with GoogleTTS, like this:
rule "Voice TestRule"
Item Voice_Robot changed from OFF to ON
say("Det er tid til at gå i seng :-)", "googletts:daDKStandardA", "chromecast:chromecast:af8126e02c056c079c04f4f925fe4e47")
The TTS is setup to use danish, so the output will be (almost) the same as the typical female voice respons from Google.
This is very a effective way due to having full control of which device to send to. The above examples send to the same Google Nest Mini which is located in my office when testing… I have several others GH devices placed around my home. I can therefore controle each individually as I like.
It´s super simple, just as it should be - I would really hate if this will ever breake or change to become more complicated. I´m not aware of any other options/speaker doing the same, just as simple… Maybe a UPNP speaker could. I havn´t tried.