I have seen a toddler who use to write a game in "pocket code" android application, he showed me his work in that way which makes me believe he is having fun doing this.
In my 4-5 years I fonded with Ancient mathematicians, what they had discovered being so early in human history and so on. Anyway programming is not only coding but also knowing some algos, and they used to know a lot of math which now is a required knowing for any kid and never boring.
More ideas from other HN users, "Secret Coders" comic book series and Coding For Kids. https://www.qwant.com/?q=%22Secret+Coders%22&t=web https://github.com/TheRockStarDBA/CodingForKids
Searching for "turtle graphics" may provide some ideas, for example https://en.wikipedia.org/wiki/Turtle_graphics
I have heard great things about the “scratch” programming, language, though it was 10 years ago.
https://computerengineeringforbabies.com/ Not sure if the author is doing another order or not