Have you heard about The Story Engine by Peter Chiykowski? http://www.storyenginedeck.com/
Together we made a free app to generate your own story prompts deck: https://cardcreator.storyenginedeck.com/
You can read more about it at my blog: https://alxd.org/the-story-engine-card-creator.html#the-story-engine-card-creator