The ornamental design for an at-home portal device. as shown and described.
The sole FIGURE is a perspective view of an at-home portal device with a display surface or screen illustrated positioned within a cabinet configuration in a home or similar space (shown by broken lines), illustrating projected life-size human images, with a capture device located within the display surface or screen to capture the image of a person viewing the display surface or screen (shown by broken lines).
The illustrations in the drawing that are shown in broken lines including the cabinet configuration are environment structure that is not part of the claimed design.