I've moved your question to the InDesign EPUB forum.
I've been looking at this too. I've check out most of the 3rd party Indesign add ons. CircularFLO seems to make the read-aloud option easiest, though I also want animations, and even though they have "over 70!" so-called animations they are pretty lame, and allow little controls over them. And you can't also have any InDesign native or imported Edge Animate animation in the document. I found that I can create much better animations easily inside InDesign. CircularFLO also doesn't have any added games or that sort of stuff. Though like I say, it is the easiest to do the read aloud markup. (But they don't answer emails.)
I am seriously considering the Aquadfadas InDesign tools, though their interface is a bit daunting, and I am finding their information on the website to be a bit inscrutable. They also have read-aloud, plus some animations and InDesign Native animations seem to work with it. They have Games as a premium add on. Though things can expensive pretty fast. Support is paid $130 for 1 issue for 12 hours. Yikes! (They also are not very responsive to email.)
The other solutions I've looked at Kitaboo, and Flipick don't see as robust and I don't like their business model. The third option is to do it ALL by hand in InDesign. Crack open the pub and add the SMIL file, hand coded, and mark up the sound files using Audacity, a very time-consuming and tedious process, that could go wrong, with many hours spent trying to figure out where it went wrong. And the third party apps look better and better. Adobe's peeps here on the forums have told me that they have NO PLANS to support any kind of read aloud tool in InDesign. WHY???? Clearly there is a need for it. I would even pay for such a tool separate from my rather expensive subscription to CC.
All of these companies are dismissive of the little guy/gal and they pretty clearly only want to help giant clients with lots of money. Nothing new there I suppose. Sigh. We're on our own.