The onboarding starts with a 4-video carousel that describes what you can do with Facetune2.
Instead of asking you to give access to your library to start tuning a picture, Facetune2 already provides a random photo, so that you can train as soon as you launch the app for the first time.
There is no tutorial, but short explanations are provided each time you click on a feature (screenshots 8 to 10).