This father has been using spaced repetition (Anki) to teach his children how to read several years earlier than average. Michael Nielsen and Gwern tweeted about the interesting case of a reddit user, u/caffeine314 (henceforth dubbed “CoffeePie”), who has been using spaced repetition with his daughter from a very young age.
Maybe just let them be children? https://www.boredteachers.com/post/learning-to-read-too-early-might-be-counterproductive