Joystick Passthrough

Unfortunately that was not the solution but I think I have narrowed down the problem (though I am not sure of the solution):

Local Device Found
  type: 046d c216
  path: sdl://0
  serial_number:  - 0
  Manufacturer: 
  Product:      Logitech Dual Action
  Release:      111
  Interface:    -1

!! Steam controller device opened for index 0.
Couldn't initialize virtual gamepad: Couldn't open /dev/uinput for writing

It looks like I need to give the Steam container write access to the host’s /dev/uinput?