Phonak and future Bluetooth

So could this mean that other brands will also have this feature?

Yes, LE Audio with Auracast capability is the future of bluetooth streaming.

Can you define a multiple stream and a multiple connection. How does this relate to hearing aids?

Don’t undersell it. Since an Auracast can be broadcasted in a form that your hearing aid pickup, such as theaters, lectures, sport bar TVs, churches and so on, I would say that it is essential to hearing for a lot of folks.

Multi-stream only means that the new LE audio standard supports streaming to two earbuds or HAs simultaneously. With bluetooth classic, the earbud or HA manufacturer had to do their own implementation to ensure both buds or HAs stay in sync.

I don’t have Phonak HAs, so I don’t know how they handle multiple devices simultaneously. Usually the problem is how you switch from one connected device to another. Does the Phonak app allow you to select which one? Do you have to turn the unwanted Bluetooth device off?

That’s where I found Auracast most useful. Right now Resound/Jabra is the only manufacturer that provides proper support from within their app. And it’s very easy to have the HAs connected to the phone and to an Auracast stream at the same time. The app allows seamless switching between the two audio sources.
If you listen to Auracast and a phone call comes in, the HAs will automatically switch to the phone call.