How on earth can you follow it on an app?
I don't buy the app any more, partly because the app being shit is not a new thing, but mainly because F1 is less interesting (you didn't know who was going to win or why), and the reasons are simple - the app gives you data which you can follow to see what is going to happen. Watching on TV just lets you know what the excitable gents in the commentary box think from the TV footage that the event producer thinks is worth showing on TV at the time.
It doesn't tell you where the other cars are, it doesn't tell you what sector times the guy in 14th who has just put on the soft tyres has, or allow you to infer what would happen if the guy in 2nd did that right now. If you're a fan of a team other than the ones currently on top, you can track what they are doing, how their sector times compare to their best, when they should be coming in to pit, what tyre they should put on, will they be switching to a different strategy...
The app can be used to follow a race, if you can't watch it in any way, but mainly it is a way to better enjoy the experience of watching the race by giving you more data. When I did have the app, I never used it if I wasn't also watching the race.