Good intel! I had already figured the link with old IGN, though. For what it's worth, I believed the 3DS proto boards were called TEG2.
Here it is, the 3DS TEG2 board: https://fccid.io/document.php?id=1272995 And another one: https://fccid.io/document.php?id=1234277
TEG title != Tegra chip. As said, TEG was also the name for the DS proto boards. I can't say for certain, but I don't think any 3ds proto boards were made using tegra chips. If were we would find some reference to it in early SDKs (much like the DS/Nitro SDK have sprinklings of Iris through out when it was a single screen device).