as the article talks about a distro for a child, I recommend a lot #debianedu .
(First of all I think 4 years old is too early to get contact with computers, even with screens in general)
My 11 years old kid has local access (no web) to tons of material about science, drawing, programming... And he is always discovering new secrets or option there.
For sure raspberry pi is a good platform for scratch, laby, colobot... Using #debian 😀