Thanks for your reply.
I can see the cmake/px4_add_module.cmake script you mention does include references to the MODULE_NAME within the target_compile_definitions() function. I can also see multiple #define mentions of the parameter within the platforms/common and boards directories.
I can also locate the CMakeCache.txt file within build/px4_fmu-v5_default/CMakeCache.txt, but I don’t know enough about the tools to say if VS code uses this directly or otherwise.
Likewise, I’m of limited use in answering your other questions about compile_commands.json. I have a fair amount of general coding experience, but I am still new to Px4 development and many of the tools are unfamiliar.
Others appear to have encountered a similar issue with the CMake tools extension and Px4, but the forum post does not contain a workable solution. I’m still not sure how related this is to my main problem with the MODULE_NAME error message.