I think I've found quite a few good storytelling apps that are engaging, with interactive elements like selecting options to guide the story's progress or designing the characters. These keep him busy while also encouraging his imagination and creativity!
Some of these apps also provide fun voices and sound effects, which little ones seem to enjoy. I find that some storytelling apps also help children understand story structure, especially if the app has an option to record and save stories that your kid created. It's a great way to encourage their budding creativity and give them a sense of achievement!
For sure, there are many ways to make storytelling itself a fun activity. I remember enjoying props and voices when I was little! But I'd love to hear other moms' methods too.