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I just tried deleting the maps app and tried opening maps://somewhere in safari. An alert popped up asking if I wanted to open the link in maps, I clicked open and nothing happened. So this needs some work.
Deleting apps from iOS 10 doesn't actually delete the app.

"The reality, though, is somewhat different, as Apple SVP Craig Federighi confirmed on John Gruber’s podcast. All you are actually doing is deleting the user data associated with the app, and hiding the icon from view. The actual binary remains on your device."

Source: As you’d expect, iOS 10 doesn’t really delete stock apps, it just hides them
 
APIs are ways INTO a piece of software. Opening the SIRI API is to allow 3rd party apps to make calls *TO* SIRI, not the other way around.

You can get Siri to send messages via WeChat or Whatsapp, what's stopping telling Siri to tell google Maps to give a route somewhere?
 
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