I find really a relaxing experience and fun to do finger doodling on my tiny mobile screen with Infinite Painter last days. It has an immense amount of excellent brushes by default and in the free version as I used, I found maximum facility of using 3 layers in total which was absolutely time saving and satisfying indeed. Along with that, there is always a chance to change your paper texture to make artworks more appealing!
Hope you'll enjoy it and try it at least once in your spare time instead of getting bored with scrolling social medias on your devices :D