fredsmith999 I did some more digging in Orion iOS with Bypass Paywalls extension running, and @fredsmith999 is spot on. In addition to attempting to set the referer to google, there are other HTTP headers it tries to rewrite for some sites (e.g. removing all cookies from ft.com requests). The WebKit framework provided by Apple offers no way to rewrite these before it fetches the pages/data from the site you're visiting, so the site returns the paywalled version.
If Apple changes their stance on this and provides a way to provide header rewriting to browser apps, we'll be able to take another try at this.