Were you able to access it right there without signal, or did you need to move to an area with coverage for it to sync?
Also, modern iPhones use tower-assisted GNSS (GPS, GLONASS, Galileo, QZSS, BeiDou, and NavIC) so the satellite isn't necessarily Navistar. With fewer or no towers, and positioned in an odd orientation on the ground, a good fix becomes much less likely, and the range can increase from <1m to 10's-100's of m.
Sure, how else would it work? But people usually don’t disassemble their phone before losing it on a train/in a taxi etc.
> modern iPhones use tower-assisted GNSS
Yes, but GP says they didn’t have cell coverage where they lost it, so that wouldn’t help.