Yeah, but the interesting part is that for a while, Samsung was the only manufacturer capable of producing LCD screens that met Apple's specs. Apple outbid Samsung's mobile division on those parts, so that resulted in a situation where the iPhone had better screens than the Galaxy, even though the iPhone's screen was manufactured by Samsung. AFAIK Samsung still manufactures Apple's mobile CPUs (likely under heavy NDA; like when accounting firms audit each other).

But you're right, being such a critical component of Apple's supply chain has likely given Samsung inside knowledge of Apple's platforms. As a result, Apple has been diversifying their supply chain to avoid Samsung.

I don't know that plays into their dominance of the Android market though. Samsung was already the top consumer electronics brand in the world prior to the release of the iPhone, so it's not surprising that would carry over into mobile phones. It was certainly a factor, though probably not a large one.