Hey BetterBizWorks! Flying indoors for real estate is becoming the preferred way for realtors to really show off their properties for many reasons. (imo) Specifically the angles, you can't get with a traditional camera on a gimbal. I think a combination of shooting with a nice camera on a gimbal and drone footage is the way to go!
Customers just LOVE innovation and the shots you can only get with a drone. Angles and shots that you cannot get any other way.
I have flown the
Mini 3 pro for this very reason. It just depends on the layout of the home, which drone I use. I would highly recommend prop guards as you mentioned. Protects your drone and the home you're filming. Helps a bit with the rotor wash as well. (a little) I personally would suggest ATTI flight mode in (most cases) not all. It all just depends...If the home has large open rooms with windows, I do like to fly with all sensors on. Smaller places, ya just can't. (Or I can't, I'm sure there will be plenty of opinions.)
I do a lot of my indoor shots with an FPV drone. It's just easier for me personally and preferred.
You probably already have done and know about this next part, but just in case...Get your part 107 which doesn't take long to get or cost much. (Also legally required if you're doing it for profit) I would also recommend getting liability insurance for sure! State Farm has worked great for me! If you get shut down the first time it's typically because the agen is newer and not aware of UAV insurance. Keep calling until you get someone. I pay 60 bucks a year per drone for a million bucks in liability insurance. Quite a deal if you ask me.
Good luck on your venture!