The ornamental design for a displayscreen or portion thereof with graphical user interface, as shown and described.
The sole FIGURE is a front view of a display screen or portion thereof with graphical user interface showing our new design. The broken lines representing the display screen depict environment and form no part of the claimed design. All text, icons, and greyscale fields form no part of the claimed design. The full line framework of the layout and rectangles are claimed subject matter.