Hello,
I am specialized in epub3 and I have just finished an interactive coloring book for children. I also have enriched a printed version book into digital with a lot of pictures and illustrations, audio and videos.
For a fixed layout epub with video, audio and images, you'll be able to have your book done for Apple Store and Android - you need as well to select your book size ; tablets and phones have different size from Apple to Android...
I am able to speak about it with you whenever you are available,
Best regards,
Penelope