The ornamental design for a breathingdeviceholder, as shown and described.
FIG. 1 is a perspective view of a breathing device holder showing my invention in use position;
FIG. 2 is a rear view thereof;
FIG. 3 is a front view thereof;
FIG. 4 is a side view thereof, in a folded position;
FIG. 5 is the opposite side view thereof;
FIG. 6 is an enlarged top plan view thereof; and,
FIG. 7 is an enlarged bottom plan view thereof.
The broken lines in FIG. 1 showing a portion of the human form, a pillow, and a gas delivery conduit represent environmental structure and form no part of the claimed design.