The first revisions were stuff made by qualcomm right? I don't think we have much data on how much customizations they make and where they their IP from, but given how much of the Tensor cores comes from Samsung I think it's safe to say to assume that there is a decent amount coming from some of the big vendors.
Apple generally tries to erase info about acquisitions from their official company story, they want it to look like internal Apple innovation.
When it comes to CPUs they bought P.A. Semi back in 2008 and got a lot of smart people with decades of relevant experience that were doing cutting-edge stuff at the time.
This was immensely important to be able to deliver current Apple CPUs.
PA Semi was kind of an interesting acquisition. The team was definitely very skilled, but there are always gotchas. Before the acquisition happened we were on their receiving end of their dual core PPC and it was not great at all. We had a lot of issues with board bringup, power, and heat. More errata than I've ever seen. We eventually had to went with x86 for the project instead, which was more performant and certainly a lot easier overall at the time.
I had previously encountered some of that team with the SiByte MIPS in an embedded context, I know they were highly skilled, they had tons of pedigree, but PA Semi itself was a strange beast.
It's "made by" TSMC as usual. Their customization comes from identifying which compute operations that want optimized in hardware and do it themselves. And then they buy non-compute IP like HBM from Broadcom. And Broadcom also does things like physical design.
