Apple AirPods Max will connect all Apple, Android and Windows Bluetooth-enabled devices. 😉

So I don't know how to connect devices to your box... but I have the Mäx with the PS5, Switch, TV and co, via Bluetooth connection works... but to connect to something else again (except Appel devices)... you have to unplug it completely🫠

Sorry, no idea, I don't know

I'm sorry I don't know exactly. I don't have an Avantree Audikast Plus.