So have a 2010 460 sport. Last year changed out the brembo's for the pro stops because of the brake dust and squeal at low speeds.

First the car with 37K miles is not a daily driver and sits in my garage. Which I think is most of the problem. Since I had the same issue with a 4runner years ago but the squeal was not as bod. Garage always seems to be a little damp because of my area and the rotors get rust on them. So I get a terrible squeal that you can hear about a block away when backing out of the garage for about 60 ft. A bit embarrassing. Then fine after I drive away.
But seems to be worse withe the LS. If I dont drive it for over 15 hours I have this squeal.
Recently we rented a beach house. And of course close by the ocean is a lot of damp weather. Noticed of course that overnight I would have the same squeal . Guy across the street had a BMW and noticed he did not have any squeal at all. Has not really noticed before. But even people that had thier cars sit for days did not have any noise.

So now I am wondering could their be any solutions.
Only had the Pro Stops with rotors turned and installed at dealership about a year ago. But it did the same with brembo's. Guessing, but maybe prostops a little louder.
Had the same problem with a 4runner in the garage but not as bad. And 20 years ago had a LS400 in the same garage and dont remember any problem.

Thanks for any suggestions