It can be easy to get kids involved in steampunk as they often see dressing up as fun, and it leads to some great inventions with the wonderful use of their imagination.
There are many resources about the steampunk genre, but here is a few for the junior steampunk aka kids:
Steampunk facts for kids: https://kids.kiddle.co/Steampunk
Steampunk books for kids:
All about steampunk art: