Embedded firmware though has gotten a lot easier (availability of cheap ARM boards with gone of flash and RAM), FOSS tool chains, there is still a mountain to climb wrt understanding the underlying hardware. Timing, keeping things synchronized while being within the power budget and stuff like that. Take a few actual EE courses or better yet if u can afford get a degree and specialize in EE. For starters can't recommend the EDX EE1,EE2 and then thr Embedded course from UTAustin also available on EDx enough. Feel free to reach out to me with any questions. My email is in my profile.