I also thought about this, but I did neither find an RFID chip that was capable of storing enough data for this, nor the space for encoded data in printable for

I also thought about this, but I did neither find an RFID chip that was capable of storing enough data for this, nor the space for encoded data in printable form. There is a commercial product for children, called Tonies (Or Toniebox) - see https://us.tonies.com/ https://us.tonies.com/. They have something called "Kreativ-Tonies" (german), where you can store up to 90min of audio content, but I did not find out, how they are working technically. I think that they just store it on a cloud server and stream / download the content on usage, but I'm not sure about this. BTW: I don't think, that storing the music on a card directly would be the best approach, because if the card breaks, you have to rebuild the whole card. If the music is stored on the device or cloud, you just have to print one.