Anyone have a specific headphone recommendation for kids using this? My daughter is 4 and we’re thinking of switching from the Fisher-Price FP3 player (due to numerous problems with its software), but I’m not sure about headphones for this one. The Fisher-Price ones are very comfy, and she has some sensitivity issues when it comes to her ears.

if the F-P headphones have a jack that looks like these they will work

The Sansa Shaker supports 3.5mm jack, so any headphone that has that jack will work fine.  If the Fisher-Price FP3 headphones has that size, it should work just fine.  My daughter uses the kidz gear headphones, it has its own inline volume control.