There are a ton of resources for this out there, and people happy to help you. I'll say this: it's a massive undertaking, it's going to cost you money, and lots and lots of time, and be longer and harder than you thought.

Given the investment you're going to make, you shouldn't try and make it harder than you have to. Ditch the idea of reusing things that aren't going to be easy, and just start with a proper aftermarket control system. It will work better, be more flexible, and you'll have lots more support when you get stuck.

Unless you're specifically looking to go down your own programming rabbit hole, and not trying to actually work on making a game. Then knock yourself out.

This is your game, so of course do whatever you like. My experience tells me your route isn’t easier. It’s certainly more limiting.

So just consider the benefits before you dismiss it. You’ll spend some money on boards. But you’ll save a ton of time and headaches and gain a lot of advances and modern conveniences.

There’s a reason most personal games, even by programmers, go that route.