My requirement
It doesn't matter what your requirement is. If you use the standard QRadioButton, you cannot change the color of the indicator to green without also changing the text color.

As I said above, the code for drawing the parts of the QRadioButton widget is very deep inside the Qt widgets implementation and cannot be customized unless you derive your own radio button and draw it yourself, you modify the QPalette::WindowText property for the button's QPalette, or you implement a custom QStyle to change the way the elements of the QRadioButton are drawn.

That's it. There is no magic solution to be found by searching. What you want to do cannot be done except through a lot of heavy work and a very good understanding of how Qt styles and widgets work together to create what you see on screen.