Inexpensive used but famous shotguns aren't lining the gun racks at stores locally, incentive money dried them up. As for a choice of what to use, each makes their own decision, I'm aware of a great many AR pistols dedicated to that role. Some may suggest a few reasons not to, consider that every firearm has it's pros and cons, and secondly, 5.56 did just fine working room to room in numerous third world countries over the last 20 years.
The Turkish market of firearms isn't considered as robust - but it's based on presumption, not fact. Their handguns are dominating a lot of defensive pistol matches and giving the EU guns a run for their money, few American brands exist anymore. We used to laugh at tupperware, what now? Same for Turkish - it's just early in the curve, get them cheap while you can. A shotgun is just a tube to ignite shells in and direct the pellets like any other firearm, accessories etc aren't going to significantly improve it's performance at 8-16 feet inside a home. Skill and practice will. Being familiar with its operation will. Take it and shoot it, even if it's those flying saucer matches some get all dressed up for, and that practice will do you well.
Even the highly popular and well regarded Mossberg Shockwave has a "defect," it requires an adapter to run 1 3/4 shells. I'd suggest finding the Turk equivalent but a recent search says all those are sold out, maybe a look at those out of the way gun stores will turn one up. Any firearm needs to be broken in, as much as the shooter to it, we're not all some sage Hickok who can ring steel on camera just for the lulz. Which leads to the next issue, now resolving, finding 12 ammo of any kind. Much like those of us who carry new 9mm's which haven't seen 500 rounds yet, and for that, maybe next year, having lots of ammo to gain proficiency in this hoarding environment is difficult. I have no excuse, just time doing other things, as a barely broken case of 9mm on my shelf says I'm being delinquent about getting out.
If you are looking for a shotgun, expect slim pickens, and if he hands you some oddly named synthetic riot gun, consider that you may need to put in some research to understand what the market offers. New guns are still coming in - old guns are not being sold much, as families loan or sell to other family members in this climate. Someone truly desperatet to make rent will be the sad seller in the near future, as rental amnesty has been stopped and evictions start rising.
For those who weren't interested, its almost two years past time to be looking for a specific firearm, and there is still a high demand for them. Things are starting to ease up, but it's not the salad days by any means. If you are trying to acquire a gun for home defense, the best time has long passed and we are now at the point where you ask for your hearts desire in one hand and take what you can get in the other. If it ignites a shell and puts pellets down the barrel, it works. Avoid the social condecension too many attach to Tribal Brands and just get one.