A pump may intimidating and all when heard, but chambering a live round may not be nearly as smooth as cycling an empty action, especially under stress.
Not kidding. I am not small or weak, but was startled the first time I took my 870 pump out and failed to chamber the first round from not being forceful enough.
By no means a shotgun expert, but my humble suggestion for a lady not very familiar with handling one under stress might be a semiauto with only a simple bolt handle to cycle and then go for it.
To hell with warning sounds.............
Just leave it chambered. Point and shoot