Curtain rod hanging - Aussie Zone

Hi all, I have a problem hanging some curtains as there is no stud above the window frame and there is already a blind hung on the frame itself. I could possibly hang it from the ceiling in one room if the boss agrees but the other room has high ceilings. Any suggestions?

How wide is the window? How solid is the window frame?

It may depend on the type of curtain as well, eg curtain rod with light material vs hand drawn with 50kg velvet curtains

If it’s not too wide, and the frame is solid, could you use bracket(s) that attach/extend from the blind brackets on the window frame? I’ve done some pretty wild stuff with angle brackets and various flat plates. Or I guess the young’uns would 3D print something…

The frame is set in plasterboard flush to the wall.
Oof. Delete my post lol