Learn C. Then maybe one of the newer systems languages like rust, zig, D, nim, etc. If you’re bored with CRUD, there’s a whole other (bigger) world to explore when you get a little closer to the metal. It’s tremendously empowering and fun as hell to get you’re hands dirty a bit, so to speak. You’ll also become a better and more employable programmer as a nice side effect.
C or C++ ? Thought about it, at the very least it would make me a bit more well-rounded.
You can also ignore the people who ignore the complexity of web apps. Classic C programs are very often much simpler than full web apps IMHO.