The ornamental design for a portable and adjustableleg-supporting seat cushion, as shown and described.
FIG. 1 is a perspective view of a portable and adjustable leg-supporting seat cushion showing my new design;
FIG. 2 is a top plan view thereof;
FIG. 3 is a bottom plan view thereof;
FIG. 4 is a right-side elevational view thereof;
FIG. 5 is a left-side elevational view thereof;
FIG. 6 is a front elevational view thereof;
FIG. 7 is a rear elevational view thereof;
FIG. 8 is another perspective view thereof in a use configuration with environment;
FIG. 9 is another perspective view thereof in a use configuration with environment; and,
FIG. 10 is another perspective view thereof in a use configuration with environment.
The broken lines used in FIGS. 1-10 depict portions of the portable and adjustable leg-supporting seat cushion that form no part of the claimed design. The broken lines used in FIGS. 8-10 depict environment of a fastening strap, user, and chair that form no part of the claimed design.