The ESP Box with the ESP32 S3 has robust bluetooth support and I don't see A2DP/BT/pairing management/etc being that big of a lift. In full transparency it's probably towards the bottom on the priorities list ATM but the important thing is it's on the list already and it happens to be something I'm personally interested in :).
But with google I’m stuck with their integration to Spotify. It’s that component I’d like control over, and that’s why I’d use willow.
That and not being spied on in my own home.
Definitely keen for one.