I go to an indoor range regularly with my handgun, but don’t know where to go with a shotgun. Is there a “practice” type shot they allow at indoor ranges if you know? Definitely all about confidence through practice.
Most ranges I go to will allow bird shot. None allow slugs unless it is outdoors and a pretty good distance.
The post by Yosemitest has several points worth thinking about.
First, in a room clearing weapon you do not want a long barrel. If your barrel precedes you into a room an adversary there will just take it from you with a sharp yank. They may grab it and push back or twist it to break your finger in the trigger guard. In any case your advantage is gone.
Second, a shotgun takes some work to be able to handle smoothly. For example a semi-auto will malfunction if held too loosely as the gun depends on the shooter to hold it firmly so the action can eject and load another round. A malfunction turns your semi-auto shotgun into a single-shot if you have not practiced clearing the malfunctions reflexively.
A pump shotgun does not do that but you must practice running the slide on the shotgun fully in order to not short-stroke it and create a different malfunction when the action is locked and there is no round in the chamber.
To do this you must practice shooting 3 round sets of shots many times to make sure you can fully run the slide every time.
Finally a shotgun hurts if not held properly. A 20 gauge pump will have significant felt recoil much like a 12 gauge.
A shouldered shotgun held loosely will hurt you enough to distract you from the important job you have in front of you.
It is not a man vs woman thing in any sense. Good shotgun work takes a lot of practice to get OK at and more to be competent regardless of gender.
Finally an shotgun is slow to reload unless you are a 3-gun shooter with a bucket-load of practice.
Hence my earlier comments about pistol caliber carbines (short, light recoil, easy reloads, common ammo).
223/5.56 rifles can be used as home defense in an urban setting with frangible ammo. Ar style, mini-14, the Tavor any of them with a carbine length (or shorter if you can have it) barrel will suffice. The blast from a rifle cartridge will be significant in an enclosed space.
Any centerfire carbine is superior to a shotgun in my opinion for a non-professional home defender due to the increased ease of use and the amount of practice required to field it effectively.