best 2018 pipeline for cross platform, rich-media experience

I am sitting on a large pile of great indesign laid out content that I want to move beyond print and make:

• cross-platform (I mean desktop, mobile, possibly set top box-living room experience)
• multimedia,
• animated and
• user reactive.

I have to admit I still cant figure know in 2018 what is the best roadmap for this. I have 2 issues:

• Finding the ultimate file format. epub3, ios app, other?
• If my starting point is indd, what is the workflow required for the best user experience that travels perfectly across platforms?

Right now I am thinking either:

1. the north face with a xcode-swift workflow for portability, security and versatility, OR
2. indd + Muse + Animate, but I roughly end up with an unprotected responsive web site (and I do not want DPS)

My priority is the quality of user experience.

This remains a newbie question I apologize for that, but I really dont know where to post it since it is cross-product.

Thank you in advance for any hint you fine people might have. I guess I don't expect a single simple solution, but hints as to where this is being discussed or debated or showcased.