Alice,
This is kind of what I thought the app was. This is kind of a Whitney Portal Store map for the early 21st century. Good enough to let you know where you are but not for serious navigation, which is what I used my map for the first time up the trail 16 years ago.
What you learn quickly here, you don't need a just follow the herd. In 6 to 9 hours most in proper shape will be standing on the summit.
Good luck with your endeavor.
