Upi Payments in Flutter using Deep link (Android and IOS)

Question

Gateway: Paytm Business for payments

Hi I am trying to implement Upi payments in flutter using Deep link.

I don't want to use any thrid party libraries like Upi_pay etc.

Deep link: paytmmp://pay?pa=paytm-67035308@paytm&pn=Reciver_NAME&mc=5812&tid=PYTM3101623366056793109&tr=3101623366056793109&am=3&cu=INR

I am using launchUrl to initiate transaction

bool launchResult = await launchUrl(deep_link_url);
print('******************');
print(launchResult);
print('******************');
if (launchResult) {
  //verifyTransaction
} else {
  //'Could not inititate transaction');
}

After launching the URL, I have integrated the Paytm API to verify the transaction status. My intention is for the flow to seamlessly return to my app once the transaction is completed. Following the return to my app, I aim to check the status of the transaction. How can I achieve this?