Anker SD Card Reader, 2-in-1 USB C Memory Card Reader for Digital Camera SD Card Viewer with Dual Slot for SDXC, SDHC, SD, MMC, RS-MMC, Micro SDXC,MicroSD, Micro SDHC Card, and UHS-I Cards

I use an Anker USB C card reader, that's the size of a thumb drive, to transfer to mobile and Desktop. Much faster, and even faster than plugging the camera in to transfer. Especially considering you won't have to make sure the camera has enough battery to finish a plugged in transfer. $17.99 on Amazon. https://a.co/d/0aZN5xmB

Any Android DAP will have the parental controls that any Android phone has. They're not a bad option, but they're an expensive option for kids who will want to end up using them like phones. I recommend the Snowsky Echo or Snowsky Disc. They are popular on this subreddit, well-made, not expensive, and the interfaces are easy to use. They both take MicroSD cards, and you don't need to buy expensive ones. Any MicroSD will work because these are JUST music players. They're not professional cameras or video game consoles, so they don't need to be expensive, fast cards. If you get this SD card reader and your MacBook has USB-C, it should be MUCH faster than a cheap-o SanDisk MP3 player. If you want headphones for these, look at something like the Koss KPH40 Retro or the Koss Porta Pro. The KPH40 Retro is new and cheap, and the Porta Pro has been around a while, sound great, and are as portable as the name suggests. The only thing is they are kinda hard to adjust for an adult, let alone for a kid. Koss is a household name in audio though, literally making some of the very first headphones. I'd go that route.

Same. Not sure what iPhone OP has but this $9 Anker usb-c card reader has been great for me. It is a blessing and a curse how small it is because sometimes I misplace it. https://a.co/d/0aXzHM3D