Inreach Explorer Plus GPS Receiver capability compared to an iPhone XS

Hello, 

Just curious if anyone has side by side comparison of the GPS receiver capability between the Garmin InReach Explorer Plus and a Apple iPhone XS Plus (or similar iphone).  When I was in Colorado hunting and and hiking in Glacier National Park with my iPhone 6s Plus and most recently in Great Smoky Mountains with my iPhone XS, my GPS receiver was able to always get a signal. Trying to determine the need for a GPS type device if the iPhone GPS receivers have been pretty good in my last few outings. Have others experienced that they were not able to pick up a GPS signal on a standard iPhone when their InReach device was able to?  I understand there are a lot of other benefits of a stand along device, but my question is only looking to understand GPS signal comparison.