Video games are a good place to start, especially for old consoles like the NES. The impacts of your experimenting are immediately visible, and they're simple devices (though the hardware "APIs" can be pretty unintuitive to a modern programmer), and there's a lot of tooling already built for hacking and reversing them. Try loading up your favorite NES game in Mesen and poke around its debugging tools with nesdev.org open in a browser. If the game you're working with has already been reversed by someone else, you may find some useful info on https://datacrystal.tcrf.net , too.

Reversing more modern software is tricky. I wrote a couple articles a while back about hacking a Gamecube game that you might enjoy:

https://www.smokingonabike.com/2021/01/17/hacking-super-monk...

https://www.smokingonabike.com/2021/02/28/hacking-super-monk...

Accompanying HN discussion: https://news.ycombinator.com/item?id=26315368