I'm on the fence about apps like Simply Piano. I have a subscription since more than half a year and yes it's fun and I'm making progress albeit slowly. But I have the impression that it focuses too much on simple songs or techniques.

When I look at the introductory piano books of my wife I'm completely overwhelmed. Like my mind is unable to process the notes without an app that tells me what keys to press. Can't really explain it. I won't cancel my subscription yet. but I think that at some point 1-to-1 interactions with a teacher is invaluable.