Hello dear people, i have been researching in ways to do this project. I have a mini Hi-Fi system equipped with bluetooth (LG CJ45). I can turn the device on and stream music or i can turn it on via the always on bluetooth. Once a device connects to it, it will turn on and start streaming.
Thanks a lot for pointing me to that guide. Tried it and played some wave files but it was not stable enough to trigger some automatic music playing through home assistant.