I really wish iOS allowed for custom search engines, it's hard coded to just google, yahoo, bing, and duckduckgo because then that would allow for this roll-your-own pattern to be accessible when on the phone / tablet (if using an iPhone/iPad).
It's only Safari on iOS that doesn't let you change search engines. If you install Firefox you can install any search engine you want and you can customize the search URL. It still uses the Safari engine under the hood, but the user facing bits are a condensed version of desktop Firefox, including tracking protection and sync.
