I have Bose headphones that pretty seamlessly switch back and forth between devices. I can be listening to music from one and get a phone call on the other, take the call and just tap play to resume music. This probably isn’t quite the same as the problem faced by the OP, but similar. I know some folks like to beat up Bose, but they have the only BT implementation I’ve every used that is really satisfactory. It “just works”. I’ve found BT in the Bolt usable, but the difference in volume between BT input and radio is pretty annoying - as well as inexplicable.