No, it’s not impossible and
No, you don’t need to use Model maker
The issue is that the method you are trying to use is not present on the TFLite model class.
You can test your tflite model’s accuracy, but you might need to copy that method from Model Maker source code and make it specific for your use case.
For example, for object detection, you can see some code here
In essence what this method does is use the model to do inference over your dataset and calculate how far it is from the target results using some specific metric.