I don't think it would be confusing if Apple implemented it like Firefox does: when I'm on a site with an OpenSearch specification, give me the option to add it

I don't think it would be confusing if Apple implemented it like Firefox does: when I'm on a site with an OpenSearch specification, give me the option to add it to my list of available search engines. Then when I'm typing in the omnibar, "Search XYZ.com for <my query>" would be an option I could tap, and similarly it would be an option available for me to choose as a default search engine in Settings.app. Apple already takes up a bunch of space in the URL bar with that stupid microphone icon for dictation that I've never used. Maybe they could put the button there.