I'd avoid modern metals like needles.
Touch hole picks ("pricks") are to remove the debris from the previous shot, and/or remove the packed-in powder in the vent after re-loading, thus lessening the fuse effect which can slow lock time.
The pick becomes a reamer if it is the same or equal hardness as the barrel/touch hole liner and has some flat edges, or at best a smoothing broach, none of which are good for the long term life of the barrel as they will eventually enlarge the touch hole.
Some suggestions:
(1) Coat hanger wire: low quality metal, can be cold formed with a hammer and anvil, cheap, available, softer than most barrels. May be easier to form with a propane torch to make tight curls or twists. Taper the point to go at least 1/4" deep into the touch hole. Can be tapered with a file, sandpaper, or belt sander.
(2) Brass rod: clearly softer than the barrel, easy to shape and form to a point with hand tools. Many hobby stores and hardware stores carry brass rod stock.
Either material can be formed into a loop to assist in clearing the touch hole. Some embed and epoxy the pick into an antler or horn tip for a handle (who cares? not historically correct but the epoxy can't be seen).
Some put the pick in the vent prior to re-loading, others use it after re-loading to clear the debris. Tried both and never found a difference. Others may have differeing results, but that's another topic.
