My recommendation is an outdoor site for irons and a location with lots of shaft options. This can be a Titleist sponsored fitting at a local club or a Premier fitting site.

My expectation for Pinehurst is the options and fitters will approach TPI or Manchester Lane for the experience. It doesn’t seem that Titleist would attach their name to a facility only at the level of a large retailer. I would also expect the Pinehurst site will be using better quality Titleist balls than a smaller pro shop. I’ve seen well worn range balls at sites like that.

Whichever option you have the most confidence as well as access.

You can get a steak at a high end restaurant, at a good restaurant, or at Dennys. All are steaks. Point being, you get what you pay for. Ideally, going to TPI Oceanside or Manchester Lane will result in the best fitting and an incredible experience. Pinehurst would be a close third. Local certified Titleist fitter would be the next level and box stores are the Denny’s of the golf world. Good luck.

I completely agree with Dale. There are different levels of fittings out there and you have to pick the one you are comfortable using. i have been lucky enough to get fitted a few times at TPI over the years. The fitting and experience will blow you away.
I also have a local fitter in my area that I completely trust and he has a very nice fitting are set up with plenty of shaft and head options. I have never been fitted at big box store so I will not offer an opinion about them for fittings.

I would think the fitting set up at Pinehurst would be as Dale stated a close third behind TPI and Manchester Lane.

Good luck and enjoy the process.