Also, in some households it works to have a chime go off if someone steps on a pressure mat in front of the door. But I think this is less used for front door alerts than it is to detect someone coming out of their bedroom at night. But if it does work for your household to put it in front of the door, it would give you a small amount of additional time before the lock was actually unlocked.
Pressure mats are one of those things that work great in some households and not at all in others because it just depends on your own family’s movement patterns. For example, if you Have a dog, you probably can’t use it, because the dog may want to lie on the mat. But it is another option to consider.
Some families also build an “airlock” around an entry area with something similar to baby gates. This can be helpful if you have a “darter,” either a pet or a child. And then that gives you yet another place to put a sensor to catch unexpected activity, either just the airlock gate opening or again a pressure mat inside the gate area. This can be done in many different styles and heights depending on exactly what you need to accomplish.
At our house we did this on the outside in front of the front door because again, I’m a wheelchair user, and I was having trouble getting in or out without the cats coming through as well. This way the cats can’t get all the way out to the yard even if they come through the door with me and then I can get them back into the house.
Depending on how much you want to invest and the architecture of the area, these can also be done in a very elegant way.