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.
Unfortunately my left one won't charge anymore, but when it did, half the time it wouldn't sync up in time with my right one.
They're not exactly name brand, so I can't complain much, but yeah that can be an issue, and it's really annoying to listen to when they don't exactly sync up.
For listening with one pair of headphones I agree, but if I want to share audio with multiple people this is definitely gonna be better than using the splitters and have the audio be quieter.