I made a file called gamecontrollerdb.txt with the following lines of text:
# Linux
050000007e0500000920000001000000,Nintendo Switch Pro Controller,a:b0,b:b1,back:b8,dpdown:h0.4,dpleft:h0.8,dpright:h0.2,dpup:h0.1,guide:b12,leftshoulder:b4,leftstick:b10,lefttrigger:b6,leftx:a0,lefty:a1,rightshoulder:b5,rightstick:b11,righttrigger:b7,rightx:a2,righty:a3,start:b9,x:b2,y:b3,platform:Linux,
03000000ff1100004133000010010000,PS2 Controller,a:b2,b:b1,back:b8,leftshoulder:b6,lefttrigger:b4,leftx:a0,lefty:a1,rightshoulder:b7,righttrigger:b5,start:b9,x:b3,y:b0,platform:Linux,
I put it on the root of my usb stick and started up the 400 mini. The Switch Pro Controller was plugged into the first usb slot and the cx stick was plugged into slot 2. The Pro controller did not work on the menus or after I started a game from the usb stick.