I was a self taught programmer who 10+ years later is now a senior software engineer. I can't tell you what to do but I can tell you what worked for me.

The reality is, I never sat down with the intent to "learn programming". Instead, I had practical ideas for things I wanted to make the computer do, and then I learned whatever was necessary to accomplish my projects as I went. Whenever I got stuck or hit an error, I'd search my questions online.

I never truly "finished" most of these early projects but they gave me a practical understanding of how things fit together. From there I just kept making stuff and taking on harder projects and then harder jobs and eventually other programmers started coming to me asking for help because they knew I had solved the thing they were working on before.

I'm not sure if it's advice, but I'd say stop worrying about learning and just do. If you like firmware, go buy some shitty unsupported peripheral from Goodwill and try to make it work on your modern system. Solve a problem you have in your everyday life. It doesn't matter if you accomplish the goal, you'll learn a lot by googling your way through it. Do that enough and you'll wake up one day and be a competent programmer.