Sorry to disappoint, but I'm old, and don't really know what an 'app' is. I did a quick search and found a couple of twenty-second glimpses, but don't really see how it helps to play music. If it's working for you, carry on; that's the main thing. I learned through many hours with the Mickey Baker Complete Course in Jazz Guitar...
... It's still available (Amazon, and elsewhere...) at a very reasonable low price. Worth every penny; I've worn out several copies over the decades, and still go back to it.
Can I offer my standard word of encouragement..?
'It's the first forty years that are the hardest, after which things sometimes tend to get slightly easier.'