As a simple test I used the "Twisty" example from here since it doesn't use javascript
:
https://cloudinary.com/blog/creating_html5_animations
I saved the epub file and then opened it in Adobe Digital Dimensions on my PC and it did animate. I opened it in calibre's ebook viewer and it did not animate. I sent it to a Kobo Forma and it did not animate.
I would think that it would not be attractive on an ereader with an e-ink display since e-ink is slow. Using an epub app on Android might fare better, assuming the app supports animations (Android e-reader apps tend to be fairly dodgy with what they support).