The below instructions describe the process for MITM'ing a target device over HTTPS using nginx. It tries to go over every aspect of intercepting traffic, including hosting a Wifi access point.
The goal is to get a target device (such as an iPhone, Wii U, or another computer) to trust our local nginx server instead of the remote trusted server. This is going to be done by importing a custom CA root certificate on the target that corresponds with the nginx server's certificate.
Client (Trusted Device) <--> MITM Server (nginx) <--> Remote (Trusted) Server
These instructions are being performed on a PureOS machine, which is Debian based. They should also work in other environments with slight modifications