Nasto

Yes, completely on device. I happen to personally know one of the maintainers and got to discuss some of the code with her. Also completely open source, so if you don’t trust the packaged apps, you could even build it yourself from source

https://gitlab.com/bloodyhealth/drip

I am running a snapcast server (on a very small VM, could be a RasPi) and have a few RasPi Zero 2W with micro-USB to USB-C adapter -> Apple USB-C to 3.5mm adapter and then feeding into various speakers/amps distributed through the house, running snapcast clients. Audio sync is absolutely flawless, devices can be grouped on demand and there are plugins for all kinds of inputs on the server. Inital setup was a bit fiddly, bit still done in one afternoon (although I admit it helped being a software engineer to compile some code myself).

https://github.com/snapcast/snapcast

IIRC there is no dedicated „Air Force One“. It’s just whatever plane the POTUS happens to be on. Of course usually that boils down to very specific few aircrafts, but if he boards the bribe-jet, this would be „Air Force One“ at that point.

Edit: I just checked. https://en.wikipedia.org/wiki/Air_Force_One