Don't hate on me, but the way I would probably do it is a single-season cartoon show.

Cartoon because I don't love most child actors, or most CGI. And, in order to lean into a lot of the subplots, you are going to want a lot or CGI or a cartoon format.

I think of Avatar the Last Airbender, and how much better the TV show was than the movie, and I think that Ender's Game is similarly better suited for TV.

Another bonus to doing a TV show with it is, you can devote episodes to Bean , Ender's shadow who has his own story ark that isn't really seen in Ender's Game.