I can now answer it myself: AAC and SBC. So-so in view of the price. Pure Apple users will not really feel any losses with AAC, but those who have an Android device should check beforehand whether it also supports AAC, otherwise there is a risk of falling back to SBC, which does not correspond to the state of the art in view of price and performance.

As far as I know, the thing only has Bluetooth, nothing else. And just via the Lightning connector with the included USB-C cable, but I don't know if this works on non-Apple devices.