Actually, an embedded web server in the Iro could be a very flexible and powerful thing. A properly done mobile website, run by the Iro itself could look very much like a native iOS or Android app. They’re never quite as slick, but it would be more than sufficient. I think that would be a great local access option.
Of course, most of the smarts of the Rachio are in the cloud, so it would be a pretty basic set of local controls.
I’ll also note that the Iro will still “run” when your Internet connection is down (or just the Wi-Fi). I think you know this, and you just meant that you can’t control it when the Internet is down, but just in case (and for others stumbling onto this topic later):
And, for completeness, there are a couple of ways to run the controller without Internet at all: