Is this why I have to wait upwards of 5 minutes to be able to actually use my SN30 Pro+ even after it's connected? I've only ever tried this docked, will try undocked today.
In my case, I just assumed it's Steam taking it's time to realize the external container takes precedence. After three few minutes of waiting it works just fine, and the UI instantly switches between XBox/Nintendo layouts and the Deck controller's layout when I press buttons on either device.
I have also done this while in desktop mode, and while the system starts registering the controller events as soon as it connects, Big Picture still takes its sweet time, and by extension using the controller to control the desktop does too.