Power steering fluid question

I’m planning to change the power steering fluid in my Tundra and got some advice from a parts store employee. He mentioned that although the truck comes from the factory with ATF, he recommends switching to a dedicated power steering fluid. According to him, a certified Toyota technician suggested this approach, and he claimed the factory only uses ATF because it’s readily available in large quantities.

I’m a bit skeptical and want to make sure I’m using the correct fluid for the vehicle.