Is it safe to carry a GLOCK with a round in the chamber?
A GLOCK is a striker fired pistol with about a 5.5-pound OEM trigger pull that has incorporated into the trigger--in the form of a lever--and when it is engaged blocks the trigger from moving rearward. To fire the pistol, the trigger safety and the trigger itself must be deliberately depressed at the same time. If the trigger safety is not depressed, the trigger will not move rearwards and allow the pistol to fire. In a way, the GLOCK trigger is similar to a double action revolver trigger.
A GLOCK does not have an external manual safety. So the trigger safety is designed to prevent the pistol from firing if it’s dropped or if the trigger is subjected to any pressure that isn’t a direct firing pull.
Best practice is to keep your finger off the trigger until you are ready to fire. Here's video that GLOCK produced that explains the trigger safety.