All existing binary modules written for Lua 5.4 are working seamlessly with LuaRT.
I'm currently working on a tutorial on how to build a simple LuaRT binary module (with LuaRT specific features such as module properties, and module finalizers)
As for an example, you have the crypto.c
file located in the src\crypto\crypto.c
that is simple to understand. This file contains the crypto module registration function with all the module functions.