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. The full line framework of the layout, the two rectangles, and the QR code are claimed subject matter. All greyscale fields (vertical field on left and three horizontal rectangles) and the remaining elements of the graphical user interface form no part of the claimed design.