Literally nothing interesting. I've only used it so far when I want to understand better how the C++ internals work: then I write a tiny program and debug it in gdb/VSCode to understand the structure better.
For example, I was recently using it to understand better how properties are stored in the kernel. I'm toying with trying to add additional functionality to properties (e.g. removing them). I'll separately write you about some other things I'm doing.