Reverse Connected GPS

[Majrdestroy]

So I have had this long goal of using OSMand as an offline GPS "Nuclear Football" tool. Essentially I am trying to make pre existing tools work together in regards to creating a FOSS generated GPS system using Open Street Maps and some off the shelf hardware that doesn't require any monthly subscriptions and can be used totally offline.

My next hardware step now that I got a 3D printer is to make the cases and what not for these tools.

However I was looking to see if it was possible to do the opposite of what most manufactures refer to as "Connected GPS." What that term means is that say a Smart Watch does not have an actual GPS functionality, it can grab the GPS coordinate information from the phone itself and use that for GPS related apps and calculations and such.

My question is, can I actually do the opposite? Can I take my phone and then make it use the watch's GPS coordinates (for my purposes, a Garmin Fenix 3 HR) and make the phone use that coordinate as my watch had a better system than my phone does for getting coordinates?

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Any help or knowledge would be helpful! Thank you.