I've always wished that Kindle had this. One can buy a Kindle translation (and some popular books have communities around translations: https://tinwhiskers.net/post/harry_potter_spanish, https://forum.duolingo.com/comment/9229774/Harry-Potter-in-S...) as well as a translating dictionary, but one must find a book that's very close to the reader's level or reading will be impossibly slow (highlight word, click to translate, repeat). Your contextual translations and next/play button are way faster.
