Hello @Lurkersoo
Please refer to blow steps from my colleague:
"
To add a file to the project, the user will need to create the file in VSCode, then add the file path to the CMakeLists.txt manually:
Open the armgcc/CMakeLists.txt then navigate to "add_executable" command:

Then add your files shown above.
To add include directories to the project, add the path to the "target_include_directories" command:

To change the optimization level, open the armgcc/flags.cmake and edit all compiler flags accordingly:

The default optimization level for Debug build is -O0, and -Os for release build.
"
BR
Alice