Android - How do I open a file in another app via Intent?
Posting my changes here in case it can help someone else. I ended up changing the download location to an internal folder and adding a content provider.
public void open_file(String filename) {
File path = new File(getFilesDir(), "dl");
File file = new File(path, filename);
// Get URI and MIME type of file
Uri uri = FileProvider.getUriForFile(this, App.PACKAGE_NAME + ".fileprovider", file);
String mime = getContentResolver().getType(uri);
// Open file with user selected app
Intent intent = new Intent();
intent.setAction(Intent.ACTION_VIEW);
intent.setDataAndType(uri, mime);
intent.addFlags(Intent.FLAG_GRANT_READ_URI_PERMISSION);
startActivity(intent);
}