If you want to learn how to deploy a machine learning model into android app, you can checkout this project. This project is too strait forward. There is tow part, one is Android and another one is Machine Learning part.
For Machine Learning part, you can check this link of Google Colab project. Where I have written a simple model and show you how to convert into TFLite model. Run the project, download tflite version of ml model and put into Androd project's assets folder. You are good to go!
Final output:
