This question is not only about software but about IO in my PoV. I would start with a small laptop having some CLI and no GUI for the sake of getting started w

This question is not only about software but about IO in my PoV. I would start with a small laptop having some CLI and no GUI for the sake of getting started with basic concepts such as keyboard and text on a screen and simple utils such as Gnu Units. Then when such a computer starts being boring it's about time to introduce GUI for the sake of reading and mastering touchtyping. Then of course you will be forced to introduce multimedia. Then it will be the internet's turn. Try to resist introducing a smartphone to the child at least before acquiring the sense of good flavor because recommendation systems of nowadays are very effective in enslaving even adults.