Yeah I considered a pi 3 with armhf debian as well. I think that might be the more sensible option to dip my toe in. It looks as though the pi 4 is faster than the pyra actually.
Seems kinda hard to lay your hands on a dev board in 2020. I'm not sure how deep into this rabbit hole I'd like to go yet, so I did wonder whether a BEAGLEBOARD BBONE-AI would be good as a rough estimate of the pyra's capability? I am aware it's only a single A15 though.
Tbh the various fan incarnations of Fate/Stay Night have gotten a bit ridiculous, they're bloated with bugs that make playing them under windows 10 hard enough at times. Really wish Type-Moon would just make an official translation.
I should probably have hung a disclaimer on this that my knowledge in this area is a bit limited. I'm a recent convert to Linux in general. I suppose the correct question might have been that if you wanted to play a windows x86 visual novel on an arm device like this (or at least try), how would...