First of all: xpadneo is the device driver for the Xbox One S Gamepad (with Bluetooth builtin) (But only for bluetooth connection - on USB connection directly xpad driver is still needed).
Now while Kodi / Libreelec supporting retro Gaming and the Xbox One Gamepads has a wide range of users - I think it would be REALLY great to get the bluetooth connection also working
Source code: xpadneo Linux Drivers
I am also available for pretesting and debugging (got one Xbox One S Gamepad) - But I only need prebuild images for testing
On current LE 9.0 (fresh setup):
Xbox One S Gamepad working only with USB connection
on Bluetooth: Gamepad connects over internal Rpi3 BT chip and also stays connected but Kodi / LE doesnt get any keypresses
On "btmon" keypresses will be recognized
On RetroPie (same Rpi3 hardware) the Gamepad works already without any issues over bluetooth - So I think its only about to implement xpadneo drivers
Have a nice day!
EDIT: Experienced in Linux - but I am not on developer side of things (no help needed on debugging / pretest purposes)