ISO Kid friendly recommendations

Hi DAP enthusiasts -

Useful information on this topic is hard to find in parenting communities, so I thought I'd ask here: What inexpensive devices would you recommend for an elementary-age child who's outgrown the Yoto/Tonie product line, but is not yet ready for an internet-connected device? Interested in a couple of price points ($30 - $50, $50-$80, etc.). Audio quality is not the main concern here.

Primarily interested in something with a good-enough file organization system: drag-and-drop loading, no fussy proprietary apps or software, doesn't require parents to spend precious time renaming audio files. So easy a child can figure it out (with supervision).

Thanks in advance