[blutack]

Additionally, phone GPS chipsets are often built into the baseband modem and performance might be limited compared to state of the art (and just price, packaging limitations for antennas, assumption that a phone always uses A-GPS etc).

The dual frequency chipsets used in modern high-end fitness watches & drones have pretty spectacular performance even in incredibly built up areas with high tower blocks or under tree cover (they usually have a barometer as well to help with the altitude problem).