I tested OpenTracks and if I attempt to “import” it brings up a file selection dialog with the “left bar” (to choose my SD card). I wonder in your case if you tap on “Fairphone 5 5G” in your screenshot on the right (from the OpenTracks dialog) if it then would allow you to tap a “hamburger menu” in the top left to then open the sidebar? But the default location already being a few levels deep on your main storage means it doesn’t at that level give you to chance to select another drive.