[steffenhk]

I've used Storyteller to create an epub book with Media Overlay but not sure it works in all ebook readers. It worked in Calibre.

https://smoores.gitlab.io/storyteller/docs/what-is-this/

[smeej]

My ereader is an Android tablet under the hood. I don't know of any apps that can do this on Android, but I can go hunting!

[sphars]

Storyteller itself does have an app, just requires you to be hosting the service: https://smoores.gitlab.io/storyteller/docs/reading-your-book...

It also says that BookFusion can read the files it produces: https://smoores.gitlab.io/storyteller/docs/reading-your-book...