About a decade ago I worked for T-Mobile on a very similar product. I would be surprised if they used any security considering during my time there, they would commonly ship hackathon projects as-is.

Fmdlocator. It can auto reply a text with location to whitelisted contacts.

Side note: Any decent kid tracker thingies that respect privacy?

Apple Watch works well as a kid tracker if they’re old enough to wear it safely, and I think the privacy aspects are very good. It uses the FindMy network, and Apple can’t see the location. There’s a bunch of specifics here. Apple Watch used to require an iPhone, but Apple made it so you can add a kid’s watch to the family so it uses a parent’s iPhone instead.

I get the idea of wanting that lifeline in case of an emergency, but I agree, constant tracking is toxic. I'd never give a corporation my kids' information just for some small convenience like that. Basically selling their future for almost nothing. By the time they grow up, potential employers and governments will know every place they ever visited as a kid, even places that might have been technically trespassing or politically divisive in the future. Kids need to learn and explore and be guided on what's right and wrong, not be punished for minor stuff they did as children their entire lives.