I spent ~5 years volunteering for a search and rescue team in New Mexico.
We definitely got the cellphone tower triangulation data. I never once saw GNSS data provided by a carrier. We used FindMeSAR https://findmesar.com/, the subject would usually text back the coordinates from the phone.
Just one data point.
The revolution that's occurred since my SAR volunteer days is the wide availability of satellite messenging on consumer phones. I'm guessing that's really changed the situation quite a bit.
We definitely got the cellphone tower triangulation data. I never once saw GNSS data provided by a carrier. We used FindMeSAR https://findmesar.com/, the subject would usually text back the coordinates from the phone.
Just one data point.
The revolution that's occurred since my SAR volunteer days is the wide availability of satellite messenging on consumer phones. I'm guessing that's really changed the situation quite a bit.