VisualGDB is designed to work with any GCC-based toolchain that is otherwise usable (i.e. can build code without errors). You can point VisualGDB to it by selecting the import option at the bottom of the toolchain selector.
Same for compiler flags like the C_STANDARD: VisualGDB shows a suggestion list based on the XML files in its own directory, but you can always specify a different value, as long as your toolchain supports it.