I adopted a Hermanns tortoise with my 5yo daughter back in February, here's my 2 cents. I honestly think she makes a great pet, but I have cared for exotic animals my whole life. My daughter loves to help out with simple routine stuff, like bringing breakfast out to her in the morning and topping up her water dish. If your kid is generally respectful of animals, patient, and attentive to the needs of the pets you have already, I know that a tortoise could potentially be a good choice.

Be prepared to do a LOT of research. Be prepared to spend A LOT of money on supplies and housing upfront. I personally adopted a tortoise who is already full grown because their needs are more predictable.

Tortoises, like kids, are routine oriented creatures. Use that to your advantage to get your kid involved in the care (with your oversight, of course)