I guess if the usb drive can't unmount properly it might hold the car awake, although I would hope they had some timeout. Worth a try.
Regarding Bluetooth, I use a Pixel phone and somehow I can leave the phone near a window and still walk outside and unlock. Further inside the house it doesn't unlock, but it holds onto a connection everywhere. During the school run, I park the car and walk around the corner and it still holds connection. I've seen a connection at almost 100m line of sight. Never has it kept the car awake.