This is amazing! For many years, I've been a happy customer (no other affiliation) of Rogue Amoeba, whose (closed-source, commercial) Airfoil software: https://rogueamoeba.com/airfoil/mac/ does all this & more (MacOS and iOS only). I've had a multi room audio setup with Airport Expresses and dumb powered M-Audio bookshelf speakers for the past 10 years going strong!
I love this project, but for folks who use MacOS and want something that simply works, I can't recommend Airfoil highly enough.
> Can Airfoil Satellite receive AirPlay 2 audio? Airfoil Satellite receives audio via the AirPlay 1 protocol. Because of this, it can’t currently be part of a multi-speaker group receiving audio from iOS.
Still a great piece of software (that I also can recommend).
I love this project, but for folks who use MacOS and want something that simply works, I can't recommend Airfoil highly enough.