Question about Motorola Moto G5 Plus

This product features the following sensors:

Finger print sensor
Proximity sensor
Accelerometer
Ambient light sensor
Gyroscope

No mentioning of a magnetometer. Is that really necessary (What does it do)? The Moto G5 Plus also supports GPS, A-GPS and GLONASS.

The magnetometer enables the compass function. Without it, the phone cannot tell the direction it is facing. As a consequence, mapping and navigation applications cannot present maps in the direction the user is facing. That is a big problem because to navigate a map you need both the location and the direction you are facing. The GPS provides de location and the compass the direction. Without the compass you must calculate the direction yourself by looking at the surroundings or with an external compass.
However the phone is not completely useless for navigation: Goole maps and other apps can calculate the direction of movement (most of the time the one you face) using the GPS location. But it works when moving and if at a certain speed, like when in the car or sometimes the bicycle. But it doesn't work well at low speeds, like when walking. And even so, the direction is lost when standing still, like at a corner or traffic light. That makes the application unreliable.
So in short, If you need navigation, make sure you buy a phone with a GPS AND a magnetometer. The European model of this phone does not have the magnetometer. I have it and can confirm so. Hope it helps others!