I remember one of the Advent of Code challenges had a hex grid puzzle on it, and Red Blob Games hex grid guide was so good the site got hugged to death because of it for a while. Used that later when I built a civ clone too, it's a fantastic resource.
I still remember a decade on the little pop of joy of realizing that not only do all the graphics on that blog post change when moving from flat to pointy, the code animates too.
The interactive graphics evoke all the fun of being a child in a science museum.
https://www.redblobgames.com/grids/hexagons/