Nice find!
For all the (deserved) bad press they got, the nMP (2013) were such COOL little machines! I'd say they're up there with the G4 Cube in terms of being one of Apple's sleekest, boldest designs.
It's really sad that Apple chose to just ignore these after release. If they'd bothered to fix the design flaw that causes the GPUs to fry over time I'm sure they could've gotten dual Fiji (R9 Nano), Polaris (RX 480/580), and perhaps even Vega (albeit likely with reduced core counts/clock speeds) cards in there! With a bit more work to help develop the Thunderbolt ecosystem (and or along side a "full size" Mac Pro), disaster could've been averted and they would've been popular machines.
I used one briefly and it was really fun to use. Fast, quiet, compact, sleek. While I don't think I'll be joining you on this journey, I do envy you. Enjoy it!