Локаль можно задать на этапе сборки

android/app/src/main/java/com/dinect/checker/MainActivity.java

@@ -49,7 +49,7 @@ public class MainActivity extends FlutterActivity {
     protected void onCreate(Bundle savedInstanceState) {
         super.onCreate(savedInstanceState);
         GeneratedPluginRegistrant.registerWith(this);
-        loadLocale(this);
+        initLocale(this);
         mPreferences = getPreferences(Context.MODE_PRIVATE);
 
         Log.d(TAG, "application prefs:");
@@ -74,6 +74,9 @@ public class MainActivity extends FlutterActivity {
                                 Map merchantIDArguments = call.arguments();
                                 mPreferences.edit().putString(PREF_POS_MERCHANT_ID, (String) merchantIDArguments.get("merchantID")).apply();
                                 break;
+                            case "getLocale":
+                                result.success(BuildConfig.locale);
+                                break;
                             case "getMerchantID":
                                 result.success(mPreferences.getString(PREF_POS_MERCHANT_ID, null));
                                 break;
@@ -146,7 +149,7 @@ public class MainActivity extends FlutterActivity {
         }
     }
 
-    public static void loadLocale(Context context) {
+    public static void initLocale(Context context) {
         Resources res = context.getResources();
         Configuration configuration = new Configuration(res.getConfiguration());
         switch (BuildConfig.locale) {
@@ -169,6 +172,10 @@ public class MainActivity extends FlutterActivity {
 
     }
 
+    public void getLocale() {
+
+    }
+
     public void handleItemClick() {
 
     }