Using another phone's GPS signal as location I have an android phone (Device A), and an android tablet (Device B). Device B has a decent GPS, but Device A's is pretty much unusable. I would like to use Device A for navigation, but to do so I need a GPS quality only Device B has. 

Is it possible to make Device A accept Device B's location as an external GPS signal (i.e. with the usage of mock location) while none of them being rooted? If not, does rooting Device A help?

I am interested in a general answer, but also in a more device-specific one if it is better:
Device A: Prestigio 5517; Android 4.4
Device B: Samsung Galaxy Tab 8.4 WiFi; Android 5.0
As a test confirmed, this is possible via corresponding apps:


on the device providing the GPS signal ("B"), you will need an app to Use your Droid as BT-GPS Mouse. An approved candidate would be Bluetooth GPS Output for this.
on the device where you want to access that "external GPS" from ("A"), you'll need an app to Use an external GPS mouse. Approved candidate for that is Bluetooth GPS.


As you yourself found out, another approach is tethering GPS with an app like TetherGPS Lite – which you write "sounds more efficient since it can be more optimized". As this waits your approval, please approve below this answer then :)