You are right, NVIDIA replaced the die for many OEMs, at the time my Vaio was affected and out of warranty, but Sony was nice enough to replace the motherboard for me and the laptop still works..roughly 10 years later..

Hard to say. Some people got temporary fixes by baking their logic boards and/or reballing the GPU.

IIRC the "recall" involved replacing the logic boards with refurbs having the same GPUs. The CPUs on the boards seemed to be throttled after the replacement.

It was likely a bit of both, but there's one thing that can't be denied, apple products are built for form over function.