[mNovak]

Possibly more feasible if you periodically capture and store a few ms raw IQ, then transfer a quick burst when the handler comes near, to do the nav solution offline.

[angry_octet]

Yep, there are a number of offline ways to solve for position. It needs 200-500mS of GNSS signal.

I like the Yabby: https://www.digitalmatter.com/Devices/Lorawan-Trackers/Yabby...

Also: http://chipfox.cz/