I thought maybe Sketchbook Pro should be a part of the Launch PSD Editor selections. It is totally FREE software program that works in PSD file format. It has a Flipbook animation (very basic), which makes for a great storybook preparation. 

iMac 27" I5 3.1 GHz 6 Core 32G 2667 MHz DDR 4 MacOS 10.15 CTA 4 Pipeline XP-Pen Artist 24 Pro