The Netkas/MVC team just posted another first !
So far Nvidia cards have been impossible to get working as eGPU in High Sierra.
The self proclaimed "experts" have claimed it's some sort of conspiracy and started a petition ! Some of them are on the "flat earth society" board as well.
Turns out it was a conspiracy of ignorance.
First screen shots on Netkas' board, more info coming here
Done on a nMP 6,1, can boot in OS X or Windows 10.
I've offered a test setup to Barefeats if anyone is interested in seeing 3rd party do some testing.