I have just updated and tagged GDExtensionTemplate for Godot 4.1!
If you want to use an existing C++ library in #Godot or use #CMake instead of #Scons for your C++ extension, check it out!
https://github.com/asmaloney/GDExtensionTemplate
It takes care of all the setup/building/linking with godot-cpp and the GitHub CI so you can focus on your code right away.