Wanted to understand if we can use UPI payment methods without using APIs from any PGs.

Have seen this flow in some apps where they directly show UPI apps like paytm, phonepe, etc. Upon entering the amount and selecting the app, the app is directly opened and confirmation of payment failure/success is given to the main app as well.

Tried finding but could not, how can I create UPI payment requests and verify them as well, without using any PG APIs.

Thanks

I could only see PGs or APIs provided by bank to implement this.