:) Thanks. Cool story. Just perusing your other posts and saw your son wanted to learn linux? Not sure how advanced he is or his inclination but could you go with the OS course from MIT? There's a good PDF book that covers the basics of a linux-style OS to give a good overview. I crammed on it for a system internals interview with FAANG. It was fun! :)

  The parallel and distrubuted operating systems group
    operating systems engineering course
      model operating xv6

  https://pdos.csail.mit.edu/6.828/2018/xv6.html