The original NVIDIA Shield Portable (just called 'NVIDIA Shield' at first) was released back in 2013, and is still a very unique device. It had the form factor of a flip handheld console, like a Nintendo DS, but was much beefier and used NVIDIA's own Tegra 4 chipset. The result was a beast of a gaming system that ran stock Android, and could stream games from your PC (as long as you had an NVIDIA GPU).
NVIDIA would go on to make two more tablets, but a successor to the Shield Portable was never officially released. FCC documents for a new Portable were filed in 2016, which were released publicly earlier this year. But out of nowhere, Reddit user /u/FwrigginRwootbeer has found a Shield Portable 2 developer unit - at a pawn shop in Canada.
According to the user, he saw the Portable 2 in a pawn shop and traded in his original model to help pay for it, unaware that the model he was buying was never released publicly. He later posted it to /r/theNvidiaShield, where others were quick to point out that the Shield 2 was never official. We can also independently confirm that it is a developer unit that was never intended for public release, and was provided to game developers for testing.
The photos match the Shield 2 FFC filing from last year. It's slightly less bulky than the original model, with smaller bezels around the screen and a modified navigation button layout. CPU-Z on the unit reports an ARM Cortex-A57 CPU at 1.91 GHz (possibly a Tegra X1 chip), 3GB of RAM, a 1440x810 display, and a code name of "loki_e_wifi."
It is definitely interesting to see an unreleased NVIDIA tablet in the wild, but it's a shame the model never reached store shelves. Except the shelves of a pawn shop, it would seem.