There's some confusion about the capabilities of the AirTags. They are NOT trackers. You cannot put it in a kid and track him. Not work like that. This thing has not GPS, not cellular. If you want to track your kid, give him an Apple Watch.
You can only see the "real time" location if the AirTag is up to 30 ft of distance with your iPhone/iPad...
If you lost something that has an AirTag, you can put it in "Lost Mode".
Apple has sold 1Billion devices but not every device is capable of run iOS13.5 that's required to send information to "Find My" network. And they need to have internet connection, so iPhones and iPads with cellular. Lot but no a billion.
If one of the capable devices comes nearby of your AirTag in "lost mode" you will get a notification: Last seen near 1234 Street. That's all. You need to go there and and try to put yourself at 30ft or less of the AirTag. It could be inside a building too...
A dog/cat lost in the suburbs will likely not come nearby any iPhone. Probably the most interesting feature of the AirTags is that you can scan it to contact the owner. But dogs and cats has tags and chips normally. Maybe useful if you miss-place you backpack...