Interesting that `javascript:` bookmarklets work on iPhones, given Apple's track record of locking everything down. Neat!
Browser extensions are still notoriously difficult to get on mobile for some reason (even on Android, which is open source-ish). So far the best method I've found for injecting JS into sites on Android is the Bromite [1] browser, a Chromium fork that allows you to install userscripts (which are like "diet" extensions). It also enhances privacy and comes with an adblocker.
In that case I’d suggest having a look at Orion, its a webkit based browser just like Safari and it tries to be close to Safari. The big difference is that you can install all extensions from Chrome and from Firefox.
Whether all extensions work is a different story but its very neat!
Its available on MacOS and iOS, both supporting extensions.
Browser extensions are still notoriously difficult to get on mobile for some reason (even on Android, which is open source-ish). So far the best method I've found for injecting JS into sites on Android is the Bromite [1] browser, a Chromium fork that allows you to install userscripts (which are like "diet" extensions). It also enhances privacy and comes with an adblocker.
[1] https://www.bromite.org/