All of the camera makers sell components to each other, but it might be unusual to sell a component that gives a competitive advantage. I've opened various cameras to see "Sony" printed on the LCD or other parts.
Nikon now uses fluorite in their supertele lenses (after bashing them as ‘prone to cracking’). I wonder if they make their own, and if so, they could be making them for Sony.
The town of Dumbsville wanted to promote dental health so they put flourite in the drinking water. The resulting paste didn't help anyone's teeth, but made the plumbers happy.