Apple Watch - locating child

My child would like more independence but we don’t want her to have an iPhone. I am considering options that would enable us to monitor her location in real time and send us notifications if she leaves a ringfenced area. I would like us to be able to call one another - but it also needs to be sufficiently cool (which the pretty kids’ tracking watch with sim that I bought doesn’t appear to be ..).

• If I bought an Apple Watch for her (series suggestions welcome please as I am looking for second hand) with cellular would this meet those needs?
• Would I be able to pair a subscription like Life 360 to it?
• Can it have its own telephone number not linked to an iPhone (ie mine) or does it need to be linked?

By way of context - she wants to ski with her friends when we are in Switzerland - and we want the comfort of knowing exactly where they are so that we can agree 🤢