According to Esper’s Mishaal Rahman, Google may soon allow you to select devices using the audio output switch in Android 13. The output switch currently supports switching between media playback sessions on paired Bluetooth devices, such as wireless headphones or a speaker.
However, the Google Cast SDK update suggests that the output switch in Android 13 may allow local-to-remote, remote-to-local, and remote-to-remote transfers. As Rahman noted, “local” refers to transfers using paired Bluetooth devices, and “remote” refers to Cast devices.
This should allow you to seamlessly stream from your smartphone to the smart display and back again using the audio output switch on the lock screen. You can see how it works in a demo published by Rahman. It also demonstrates a forthcoming “stream expansion” feature that allows you to enable audio playback on multiple Cast devices simultaneously.
Two years ago, Google was already working on adding support for Cast devices to the Output Switch. However, for some reason, it has not been completed. Now that Google describes this feature in developer documents, it may be implemented in a forthcoming update.