Not really. The phone only appears "off" but is in-fact in a low power mode providing beacons. It won't work if the battery were removed.
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.
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.