I can do this with my Note 20 ultra. It's a Bluetooth 5 feature. We can also have multiple sources connected to one speaker. This all has nothing to do with Android 16.
I had been using samsung devices and lg devices for quite a bit and I could send audio to two bluetooth devices with the note 8. I had always carried two devices, my other device was the a32. I had thought it was something that was a normal thing. then I upgraded to an xperia 1 III. a while later I then tried to send audio to two different speakers. I first connected to one of my speakers and then tried to connect to another one at work. it did connect, but it disconnected from my speaker. looking around I find out that it was a pretty much samsung only thing. opening up the ability to all android devices is a good thing.