The ornamental design for a nasalsplintdevice, as shown and described.
FIG. 1 is a front, top, and side perspective view of a nasal splint device illustrated positioned over a person's nose (shown by broken lines); and,
FIG. 2 is a side perspective view thereof.
The illustrations in the drawings that are shown in broken lines represent the environment or structure that is not part of the design. The stippling in the drawings indicates a contrast in appearance.