@cbowdon I did just start and we haven't spent more than a couple hours on it so far. I made the mistake of (re)introducing him to Minetest at the same time, so he's mostly been doing that so far.

I do have a 3yo as well that has been opening Scratch because he enjoys putting various sprites in the scene, and he'll ask me to do some of the things I did with my older one, like have them chase another sprite and say "ouch!", or make sounds, etc. And I'll show him some other things. But he's interested in the result, not how to do it. He wants to help with the blocks and typing, but that's just to be involved; he doesn't grok any of it.

So I think it's entertaining to a 3yo, but it'll be a while before I see whether him experiencing it now will make him more easily get into programming with it in the future, or if he'll already be sick of it by then.