I claim, the ornamental design for a display screen or portion thereof with icon, as shown and described.
FIG. 1 is a front view of a display screen or portion thereof with icon, showing the first embodiment of my new design;
FIG. 2 is a front view thereof in an environment of use; and,
FIG. 3 is a front view of a display screen or portion thereof with icon, showing the second embodiment of my new design.
The evenly spaced broken lines illustrate the display screen or portion thereof. The dot-dash broken line illustrates a boundary line. None of the broken lines form part of the claimed design.