The ornamental design for a footballfansupportboostingdevice, as shown and described.
FIG. 1 is a top front perspective view of a football fan support boosting device showing my new design, wherein stitching and laces of a football and a flag are shown in broken lines and form no part of the claimed design;
FIG. 2 is a front elevational view thereof;
FIG. 3 is a rear elevational view thereof;
FIG. 4 is a right end elevational view thereof, the left end elevational view being a mirror image thereof;