Answer ( For future, if anyone encounters same problem )
Thankyou everyone for not responding to my request, however I found the the problem causing this error which was in this line of code:
String shelfGuageMap = '{"14": 2, "16": 1.5, "20": 1}';
String angleGuageMap = '{"14": 175, "16": 150, "18": 130}';
Map<String, dynamic> shelfGuages = json.decode(shelfGuageMap);
Map<String, dynamic> angleGuages = json.decode(angleGuageMap);
Seems like flutter flow does not support String to Map conversion on android or at least not in my case, So I changed the whole logic to:
String shelfGuageList = '["11:3", "12:2.5", "13:2.5", "14:2"]';
String angleGuageList = '["11:140", "12:150", "13:160", "14:175"]';
List<String> shelfGuageToList = json.decode(shelfGuageList).cast<String>();
List<String> angleGuageToList = json.decode(angleGuageList).cast<String>();
Now, don't know why this was an issue but Code is finally working on all devices.