The KML format is one of the supported output formats of GPS Wizard.
KML only contains the latitude and longitude of track points but they will retain the underlying precision; typically 7 decimal places.
This is mainly intended for anyone who wishes to display GPS tracks in Google Earth, etc.
I also considered using the FastKML library but in the end, just wrote some custom writer code using lxml.
The significance of <trkseg> elements is clarified in the GPX schema:
A Track Segment holds a list of Track Points which are logically connected in order. To represent a single GPS track where GPS reception was lost, or the GPS receiver was turned off, start a new Track Segment for each continuous span of track data.
So, individual <trkseg> elements should be converted to individual <LineString> elements when saving a GPX track in KML format.
This therefore necessitates the use of a <MultiGeometry> element in the <Placemark> element(s) of the KML.
Support for the following:
<LineString> for each <trkseg> within a GPX file, etc.