The Glock has three safeties designed to prevent the weapon from firing if the trigger hasn’t been pulled correctly. One of these prevents the trigger from moving backwards unless it is depressed inside the trigger guard. You clearly know all this.

The term you’re looking for is “affirmative safety”, one type of which would be the common switch on the side of the frame that prevents the trigger from being pulled until it is disengaged in an action distinct from pulling the trigger. The Glock does not have an affirmative safety.

Source: certified Glock armorer