Update: I got the steering wheel controls programmed using the Joycon EXR today! Wiring it up to the car was easy thanks to detailed instructions from forum user bigaudiofanat in scope22's
thread; Thank you! The programming process was straightforward after watching some youtube videos. I did have to make adjustments to the sensitivity screws on the joycon board in order to read all the buttons. Speaking of buttons, I was able to detect 5 buttons (Source, Switch Up, Switch Down, Volume Down and Volume Up) which you can program a short and long click for each, so a total of 10 buttons really. I keep seeing documentation on making the joycon EXR detect the reverse light and I think that's my next little project for the tablet.