I am looking for a free dashcam application that I can extract GPS tracks from the saved videos (possibly using FFprobe).
To extract GPS information from video you can use
exiftool. If you want plaintext format you can use command:
exiftool -ee video.mp4 >output.txt
if you want to have GPX format as output you can use command:
exiftool -p gpx.fmt -ee video.mp4 >output.gpx
gpx.fmt file can be downloaded from here. You will need
exiftool version 10.49 or later.