Max The widget runtime is sandboxed, so it can’t launch system panels, control Bluetooth audio routing, or open Android settings menus. Those actions require full native app privileges, which widgets simply don’t have access to.
Also, if you want to quickly switch the audio output, just swipe down the Quick Settings panel. In the media player controls, you’ll see a device switcher button in the top-right corner that lets you change between connected audio devices easily.
If I’m wrong about any of this, somebody correct me. And if it’s somehow possible to build a widget like this using Nothing Playground, then I’d genuinely love to see someone try it.