Configuring hold amplifier as media player

Hello all

I have an old amplifier and I want reproduce Spotify and, if there is a way to create an FM radio in home assistant, the FM radio

I can connect it to the raspberry 3.5mm jack or it is connected as bluetooth device and it is one of the possible output in Google Assistant

Is there a way to define it?
Is there a way also to control the volume via broadlink?

Thanks all
Claudio