Press and hold SELECT+LEFT to switch to what they are calling "Steering Wheel Mode". This changes the left analog to output digital values of 0 to MAX, instead of 36 to MAX effectively disabling the deadzone.

Press and hold SELECT+UP to toggle back to the default mode.
https://www.brookaccessory.com/download/Dreamcast/
https://www.amazon.com/Brook-Wingman-Co ... 08CGCWKH5/
And don't forget on a two analog stick controller:
SELECT+RTS (Right Thumb Stick) = Becomes Dreamcast Analog Stick (swap sticks)
SELECT+LTS (Left Thumb Stick) = Standard setup
Second thumbstick outputs face button values.
Also, did some testing with this tiny controller, the 8BitDo Zero 2, with the WingmanSD. It does work WIRELESSLY when configured to Switch mode. If you would like to use X-Input mode, you'll need to purchase a Mayflash NS-2 Bluetooth adapter or a Mayflash NS-Lite Bluetooth adapter to connect to the WingmanSD USB port. https://www.amazon.com/Bluetooth-Gamepa ... 081HML6MP/