Do you know of any examples of doing something more complicated like this with Godot and C++ (past the normal docs)?... I've got some existing C++ game engine stuff I'd like to integrate with Godot for managing rendering side of things.

https://www.youtube.com/watch?v=xo3z9IjGRSo

My colleague made this 3 years ago before we released our first game.

Basically we forked Godot, setup VSCode to compile it, and add new classes to a <repo>/modules/<project_name> folder and it works great. Since this video we've made a suite of macros that allow us to bind variables and methods to the ClassDB in 1 line each. Way nicer than default godot technique for adding new variables/methods.