I absolutely love the Switch version of Spintires. But, unless it has been modified in with the new Old Timers DLC, playing it with a Gamecube controller is impossible.
Having full compatibility, with proper vibration and analog trigger support would be nice but, simply having multiple (more adapted) controller layout options would be enough.
The main problem is that the triggers when using Gamecube controller are attributed the small L/R buttons on Switch (as opposed to the very trigger-like Lz/Rz buttons because Nintendo is Nintendo). So when playing the game, I have no brakes, no way to Switch the camera, no real ways to use the menus and I have to press the tiny purple Z button to accelerate.
I was honestly surprised this wasn't fixed the last time I played the game...