It might not be entirely relevant to your situation since this happened at the start of my career but I somehow ended up going from Ruby on Rails development to working on C++ networking code in the games industry. The way I did it was by starting with backend development on games and eventually getting to work on the internal SDK used by the different projects to communicate with the backends. I now work as the equivalent of a full stack developer where the frontend is a game engine running on a console devkit instead of a JavaScript SPA running in a browser. This might be some form of survivorship bias but getting your foot in the door of a new industry/area with some skills you already have and slowly moving towards what you're actually interested in worked for me.