At the moment modRana can unfortunately only record GPX tracklogs, not display them. GPX tracklog display is certainly planned, just not implemented in the Qt 5 GUI used on Sailfish OS.

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ModRana actually has support for parsing GPX files and can show them on the map in the GTK GUI used on other platforms.

The Qt 5 GUI needs:

• UI for selecting which tracklogs should be shown
• some Python & QML code to show the GPX tracks on the Canvas that is already used to draw routes
• possibly some optimizations if long GPX tracks should be shown so that they are not drawn all at once and only the visible part is drawn and the point count is reduced when the map is zoomed out and the whole track is visible

Once these are done it will be possible to show GPX tracklogs in modRana on Sailfish OS.
</technobabble>

In the meantime I've tried searching which native Sailfish OS apps can display GPX data and it looks like Maep Qt can do it.