Career in Compilers and Operating System

I am currently working as a manual tester. I have been using C++ as a hobby (writing game tools) for around 3 years. Now I stuck with this job and barely programming or not at all nowadays. I just want to switch my job after 1 or 2 years.

So I’m really confused what career path to choose. Idk why I want to specialise in compilers - all I can think of is how amazing that program is and I want to deep dive into compilers. I can remember enjoying so much learning Theory of Computation in my academics. But I feel is it really worth it ?? Should I make that my career ?

I just don’t know what to focus on in my spare time. I want to know if there are demand and opportunities in upcoming years 2026 and beyond.

I just can’t explain my feelings - should I do what I love and go for it (or) get promoted in current job ( to automated testing - which I don’t want or love) and move on as a normal person would choose I guess.

How do I start learning compilers from scratch ? And contribute to OSS projects. I guess there is a huge gap between industrial projects and theoretical compilers subjects + writing some compiler for some language.