How to browse internet in the app browser itself

Hi there,
I am integrating payment gateway in my app and I have a requirement where I have to browse the internet in the app itself. I know I can work a way around using INAPPBROWSER but I want it to happen in the app itself. I tried using iframe in the app. It worked fine until I login in any bank account and then it is asking to redirect to browsers in my phone. Happy to hear how to do that.

If this is my work, I make my RestAPI (use Server Side Language) and connect.

We don’t have any control over payment gateway. We just have to call the api & it will give us callback at the end. How we are gonna render these things through server?

As I am new to this framework please tell me how to do
RestAPI (use Server Side Language) and connect.