It would be great if you could support *.fit files.
thank you for your suggestion. Fit format is similar to tcx, we have evaluated adding support for tcx files and we came into conclusion that it won't be a good solution for our GPX Viewer app. GPX Viewer app will support only gpx, kml and loc formats. You can at any time convert fit and tcx into gpx or kml files using this online tool: https://www.alltrails.com/converter .