It exists a similar tracker to the airtag by Samsung but idk if you can trust them anymore than apple. I have a 9 year old step sis and with her we have had problems with her because we couldn't track her. In her school phones arent allowed at all. My mother and my stepdad really doesn't care about privacy or security their use windows China phones etc. they usually use an app provided by google " family " I think it is called there thy can also lock up the phone etc.

I am glad that I don't have the problems to be honest with you. What I would do is to look for a device that can do the job for me were the server can be selfe hosted. If literally nothing exist I would try "do it myself"

If you selfhost a nextcloud yourself this will be easier idk to be honest if this is up to date anymore and if its real time but check https://apps.nextcloud.com/apps/phonetrack Set it up and glue if possible a small phone that you trust on your girl and you are ready to go

Alternatively look for a mini pcib PC like a raspberry pi zero or something like it put somehow a Sim card in there and get it to work (good luck with that). Program a software that pings your server once per minute or every two. Then you would have to make a case were you can put your mini tracker and a powerbank into. And hang this device to a belt that your girl would have to were

I know that is a very stupit way but hey more private it cant get