Ask HN: How to “level up” as a software engineer?

After nearly a decade in the industry, the long term career prospects of being a rank and file web developer hacking on React UIs seems tenuous at best. What's the best way to go about transitioning to "real" software engineering i.e. systems development, aerospace, finance, AI/ML, etc.?

I find the future of the web platform dubious, and staking my entire livelihood on its' existence is increasingly a terrifying thought. What are the most in demand skills outside of web development?