Have you tried motion steering? A Pro Controller is comfortable to hold and use. If you're looking for something wheel based, you have the HORI Kart Racing Wheel or the Pro version, one of them handheld wheels which a single joy-con fit, or the Numskull Joy-Con Steering Wheel.
I've spend time today looking at how best to play Grid Autosport, which isn't an easy task. For Grid Autosport I'm using a Mayflash adapter with an official GameCube controller, which seems to be the only way to make the triggers somewhat work like on other consoles. Every other option it seems the car will be at 100% or 0% throttle.