How to modify headers with Safari on iOS

I've been looking for this same solution. I need it to test engineers' in-flight changes to a web platform in Safari. I need it both for desktop and iOS.

I have the same issue all the time, when in the office at least i could share my laptops network connection (and thus routing for testing restricted apps) but now I’m dead in the water

I want to use Safari for my GraphiQL page testing but with the added security of an API key, I have no way to edit headers to allow access to the GraphiQL interface. Firefox and Chrome both have extensions to edit headers, and the rails-graphiql gem is testing the implementation of editing headers directly in the GUI. But until that update get's pushed, there's no solution I suppose.