title: Open KML/GPX files in appropriate external map app
body: <p>My Flutter (Android and iOS) app generates KML or GPX files, which works as expected.</p>
  <p>Now I want to add a button &quot;Open file&quot; which should open such a system dialog where the installed map or other consuming apps (which can handle such formats) are listed to be chosen.</p>
  <p>How can I open this dialog? How can I find the format-related apps and how can I send the file to these apps. I guess, there is a plugin for this, but couldn't find one. It must work on Android and iOS, nice-to have is web support.</p>
  <p>I just saw <a href="https://pub.dev/packages/open_file" rel="nofollow noreferrer">open_file</a> but I am not quite sure, if it works as expected because it doesn't list support for KML/GPX.</p>
  <p>Thanks in advance!</p>