@seb How about GCompris? Or maybe something like TuxPaint? Tux of Math Command? Those are the three I remember. Hope it helps!
@seb Idk if you consider this "kindergarten level" but how about: Kanagram and Scratch (might be a bit "too advanced")
I am babysitting my neighbours son every week (he's currently 4) and he enjoys Kanagram and Scratch a lot.
He doesn't understand the purpose of Scratch that much, but atleast it keeps him busy?
INDICATORS OF COMPROMISE (IOC)
InfoSec Community within the Fediverse. Newbies, experts, gurus - Everyone is Welcome! Instance is supposed to be fast and secure.
We have a Getting Started Guide here: https://ioc.wiki/mastodon
HAVE FUN and STAY SAFE!