To use Separate App Sound on a Samsung Galaxy phone, go to Settings > Sounds and Vibration > Separate App Sound, toggle it on, choose the app (e.g., Spotify), and select the audio device (e.g., ...
You can use SoundSource 6 to create a group of audio output devices, including Bluetooth speakers, wired headphones, AirPods, AirPlay speakers, and literally any other audio device your Mac can ...