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 may not be available in some browsers.
In the era this thread was written, you didn't know what you were getting into until you got there (though the stations were still generally very reliable.)
These days the car gives you real time status for sites that are closed or even have reduced services - and the Nav won't route you through one of those.
FWIW, there is a lot of good information on Supercharger being built, operational status, etc in the various region sub-forums. Here is the link to the one that contains info on Knoxville, Southeast.
Some people are quite active in these regional sub-forums and provide pictures of the construction, or broken equipment, service center personnel, etc.