Flutter App – UPI Payment Module (Without Payment Gateway)

We are working on a Flutter app and need to add a UPI payment feature for Android.

What We Need:
A button in the app to pay via UPI
When user clicks, it should open any UPI app like Google Pay, PhonePe, etc.
After payment, the user should return to our app
In our app, we need to show:
Transaction Status (Success / Failed / Cancelled)
Transaction ID
Any other UPI response details if available

No Payment Gateway:
We do not want to use any payment gateway like Razorpay or Cashfree, as they charge for UPI.
Only need direct UPI (Intent-based) with no extra cost.

Work Plan:
You will develop this as a separate demo app
Once we approve the demo, you will share the code
We will add it into our main app
If needed, you should support us during integration

Payment:
Share your fixed price for the complete task
We will create a milestone
Full payment after testing and working delivery

Note:
Only experienced Flutter developers
Must have worked on UPI or payment before
If you have better ideas (without any charges), we are open to suggestions

Looking forward to your proposal.