Galaxy Buds Live autoplay

Depending on the app you're using, you can disable this in settings. Poweramp allows you to turn off "Resume on Wired Headset" in the settings menu. If you have PowerAmp as your default player, this will prevent that.

Not sure if you've figured this out yet, either, but the music automatically pauses when placing or receiving a call. So the device definitely recognizes that it has phone capabilities that need to take priority from time to time.