Better question, why bother?
What does it take to reload a shotgun shell? Minimalist approach.
No dies/presses needed.
A hammer maybe, substitute a rock in a pinch. A metal pin to not out the spent primer, find that in the rubble. A flat surface.
Wadding? I can use any sort of fabric, my shirt sleeve maybe.
Load? Find that in the bubble. Maybe wax it together and make a Freud slug.
Primers? Yes I will need these, but I can easily carry thousands on my person or in a bag.
Powder? Yes, will need a sourse.