... both on macOS and iPhone.

need a phone, he or she needs a human being from whom he can learn, to whom he can turn whenever he feels the need to, who will protect, comfort, and support him. If you can't be with him or her long enough, find someone who can. You sure aren't the only person facing this problem. Technology is not the solution you're looking for, after all we're talking about raising a human being.

... exists. But as mentioned by bondsbw, you can't control wether it sends your keys to a third party.