Apple iPod Shuffle 2nd Gen vs Mighty - Need help with Apple Music

Our 10-year-old has become very interested in having his own music, so I was going to buy him a Mighty, which reminded me of my old iPod Shuffle.  When I realized the Mighty only worked with Spotify (and we are an Apple Music family), I looked for another option.  That’s when I found my old iPod Shuffle 2nd Generation in perfect condition.  It was fully loaded with all my music from 2012 and would be perfect for our 10-year-old.  Then I thought to add the playlists he recently created on Apple Music so it was fully loaded for christmas.  That’s when everything went downhill.  I had to restore and update the iPod to a newer operating system.  I did that, and now all my music from 2012 is gone, and I’m unable to add it to any of our playlists from Apple Music.  I no longer have my CDs or MP3s from that time.  I rely entirely on my Apple Music.  What can I do?  Can I get our Apple Music playlists on my son's iPod shuffle?  What are my options?  I can not simply go back and buy all the CDs I once owned to add them back, and I can’t load anything I currently pay for with my Apple Music subscription.  Do I abandon Apple Music and get him the Mighty Spotify?  Does anyone have any experience with this?  Any pointers?  My son is 10, and we don’t plan to get him an iPhone for another three years.  I have considered an Apple watch, but he's not responsible enough yet and would likely lose it.  Please advise.  Thank you!!