What are some alternatives?
When comparing Flowkey and Skoove, you can also consider the following products
Simply Piano - Fast and fun way to learn piano
Synthesia - A fun way to learn how to play the piano.
Pianu - Learn to play the piano in your browser.
Playground Sessions - Online piano learning game.
Yousician - An interactive guitar-learning app.
Piano Marvel - Online Platform to interactively learn Piano and Drums on your own or with a real Teacher.