At least that's what the grapevine says about how that came together.

This is when I stopped reading because this is demonstrably false. The 214 scratches the Cortex 53 cores and is semi-custom hardware. That also ignores the obvious deal to cheapen the Tegras, which was basically handing NVIDIA the Chinese market on a silver platter, which Nintendo really didn't cater at all...

AMD had nothing low power/long battery to offer but the jaguar at the time, so Nintendo had to deal with one of the most hated companies in order to get a competitive mobile chip, rather than doing it in-house with licensed off the shelf ARM chips like before. They took a page from SONY and went with a custom GPU based solution, but lacking a solid hardware department (AMD did a lot of the heavy lifting over the years) they just went with NVIDIA because there was almost no other game in town at that price (see Chinese market above, no one else was trying to get into streaming for the Chinese market and needed a strong game library).

That's it

Edit: regarding output switching... You must be using an apple phone and never heard of MHL... Jesus... It's like with Apple fans, shit exists for a decade but they honestly think it was Apple that came up with it. M8, and let's not start with the joycons, they are pretty shit, prone to failure and the design is so garbage that even Nintendo spent R&D not to use that trash sliding mechanism again...