on Android definitely works offshore
well out of range of any cell towers.
I develop Android apps, including ones which use location data.
A developer can't decide what is used to determine fixes (4G or GPS), they can only make calls to the operating system's "Location Services" to get a location.
It's the Operating System and User Preferences that determine how fixes are obtained.
The only reasons that an application would only work with cell data is if:
1. the user has set "Location Mode" to "Power Saving"( "Uses Wi-Fi and mobile networks to estimate your location")
rather than "High Accuracy" or "GPS only"
2. he has a really cheap
device which doesn't have GPS - but there are very few of them on the market.
(The above is of course only talking about location fixes. If an application needs a data connection to do other things such as download maps, then obviously that part of the app won't work outside of WiFi
or Cell range, but location services still will. But I don't know of any navigation
app that doesn't cache maps/charts for use outside of cell range).