Google Maps directions limit - flutter

Question

I have an app that opens routes created by other users. In first essence, if a user does not have an app that supports .gpx files, the app will tell the user to simply get a supported app e.g. Strava.
But then it came to mind that perhaps I could merge the lattitudes and longtitudes in a Google Maps url.
String urlStart = "https://www.google.com/maps/dir/";
LocationParser locParser = new LocationParser();
List<LatLng> latLongList = await locParser.parseGPX(Uri.parse(route.file!));
latLongList.forEach((ltlng) {
urlStart += '${ltlng.latitude.toStringAsFixed(3)},${ltlng.longitude.toStringAsFixed(3)}/';
});
Uri uri = Uri.parse(urlStart);
launchUrl(uri, mode: LaunchMode.externalApplication);
as you may expect this url becomes huge and the Google Maps app is not able to handle this input. It is however able to handle the following url:
for (int i = 0; i < 50; i++) {
var ltlng = latLongList[i];
urlStart += '${ltlng.latitude.toString()},${ltlng.longitude.toString()}/';
}
Update
I figured the main issue is url-length. I only want to open Maps thus perhaps there is a way to send the directions directly to the app other than opening a maps url? If not I have to have peace with the fact I cant do it

Answer 1

For example, some parameters use a pipe character (|) as a separator, which you must encode as %7C in the final URL. Other parameters use comma-separated values, such as latitude/longitude coordinates or City, State. You must encode the comma as %2C. Encode spaces with %20, or replace them with a plus sign (+).
Additionally, URLs are limited to 2,048 characters for each request. Be aware of this limit when constructing your URLs.
SOURCE: Constructing valid URLs