Those watches with tracking built in are certainly popular in my area, but I absolutely refuse to use it. Kidnapping just isn't a thing (the majority of kidnappings is by a trusted family member/friend), and I don't think kids should get accustomed to someone constantly looking over their shoulder. I've gotten my kids "smart" watches (fun Minecraft watches with built-in games and whatnot), and there's no tracking or internet access whatsoever.

If kids need to call, they can ask a trusted adult to borrow a phone. If I trust my kid, they can borrow my spare. Kids don't need a phone of their own until they can at least get around on their own (e.g. driver's license or parental permission to leave the neighborhood on their own), and for me, that's like 14yo. I have a 10yo, and there's no way I'm giving them a phone now or in the next year. They're really responsible, but they don't need it at all.