Yes, this is definitely possible — and quite common!

Since you already have a RESTful web service providing temperature sensor data (even if just on localhost), your Android app can fetch that data using HTTP requests.

Where to Start:

Make the API Accessible

If your REST API is running on localhost, your Android device won’t see it unless both are on the same network and the server is bound to your local IP (e.g., 192.168.x.x, not just localhost). You may need to expose it using a tool like ngrok for testing.

Android Side

Use libraries like:

Retrofit or Volley – to make HTTP requests

Gson – to parse JSON responses

Steps:

Create a basic Android app (Java/Kotlin)

Add a network permission in AndroidManifest.xml

Set up Retrofit to call your API

Display the data in a simple UI (like a TextView or RecyclerView)

Example Use Case:

If your API is at http://192.168.1.5:3000/data, you can fetch it and display the temperature values on your app.

If you're experimenting with real-world use cases in IoT or sensors, this is a perfect starting point for applying what many mobile app development agencies offer in production-level apps.