https://pinballmakers.com/

Skip using an Arduino and reinventing the wheel. Instead use one of the existing controllers - I recommend P-ROC - and concentrate on making the game.

You say you have “ all the stuff you need” but then talk about all the stuff you’re missing.

I’ve seen so many projects started and then abandoned when they run into issues using homemade driver boards because it turns out that doing that part is surprisingly difficult. I just thought I’d offer a voice of experience to say, skip the low level stuff and get right into the fun part.