@Komfudo @torepang linux has already been ported to the 3DS, so it would be easy to get nginx running on it.
But from what I can see the wifi chip isn't supported so you'd need to figure out a way to get it to talk to the outside world to actually act as a server (implement a wifi driver or hack up some other means of communication like a serial port).
https://github.com/linux-3ds/linux/wiki/Driver-and-platform-support
@jiub @Komfudo my bad. fat finger posted.
i wonder if nginx has a version for the ARM cpu that the 3ds uses. i'm not too familiar with ARM cpus so i might just be overthinking a bit.