While what you describe is possible, it’s not implemented in the app. Logging is only done to the SD card.
It’s not difficult to do what you want though. Use the mooshimeter logging as normal. Then find a GPS logging app, on Android I recommend “my tracks” by Google; there must be others on iOS. Log your position over time with this.
Then it’s a matter of combining the logs. Unless you are good at Python, I’d recommend doing it in Excel. Export both legs to CSV and load them into Excel. Use vlookup to find the GPS position corresponding to each voltage, or vice versa. If you are not happy with the results, you might need to search the net for “piecewise linear interpolation Excel” to find the formula for this.
One tricky thing might be the time synchronisation. The mooshimeter might not record actual time, it may just be seconds since it was started. Then you’ll have to enter an offset that corrects the time difference. It might help to put a signal into the data, like only connecting the meter to voltage at a specific exact time, so you get confirmation that your offset is correct.
This would be the sort of app that gets created by the user community, if the API were made available. James, would you consider adding a socket to your app, that allows other apps to query the meter?