You can install our site as a web app on your iOS device by utilizing the Add to Home Screen feature in Safari. Please see this thread for more details on this.
Note: This feature currently requires accessing the site using the built-in Safari browser.
Tesla knows. They tabulate it for their reports to the NTSB. I've seen regulatory reports where it is somewhere around 10% of all Tesla historical miles. But I agree with Saghost; it's nowhere in API for now.