If you choose to build the taxi app from scratch, here are some steps you can follow:

Define the app's requirements: Start by identifying the features and functionality you want the app to have. Consider things like booking a ride, paying for a ride, tracking the driver's location, and rating the driver.

Design the app's user interface: Next, create wireframes or mockups to visualize how the app will look and function. This can help you refine the user experience and ensure that the app is easy to use.

Set up the development environment: Install the necessary software and tools on your computer, such as Android Studio and the Android SDK.

Implement the app's core functionality: Use Java or Kotlin to write the code for the app's core features, such as booking a ride, paying for a ride, and tracking the driver's location.

Test the app: Test the app thoroughly to ensure that it is stable and performs as expected.

Publish the app: Once the app is ready, publish it to the Google Play Store or another app store.

Building a taxi app from scratch can be a challenging task, especially if you are new to app development. It may be helpful to work with a team of developers or seek guidance from online resources or communities.