Does iPhone use Messenger GPS Location Data?

If the Messenger device is paired with an iphone, will the iphone use the device's (Messenger) GPS coordinates if the iphone loses its own GPS signal?

I am having a bear of a time deciding between Mini 2 and Messenger because I can't figure out how reliable the iphone is in the woods. I read something from a respected gear review site that said most outdoor enthusiasts use a smartphone for GPS now.