Since the debugger is gdb, can I simply access the gdb command line interface (CLI)?
Yes, partially. To access the gdb CLI, select the gdb process node in the Debug view. The gdb command line will then be available in the Console view. Though no prompt is visible, you can enter commands at the bottom line of the Console view. Doing so may desynchronize the IDE and gdb, so be careful when driving the debugger using this interface.