My son and I made a video game when he was 6 (started at least). I did 99% of the coding, was 3d and math a little advanced but he drew it out, recorded audio and did a lot of research and work for it.

If the kid is excited about project you don’t need to explain much, it’s more holding them back from grandiose ideas. Kid doesn’t need to be a genius, hard work trumps that.