I saw a guy on Youtube with a strong slingshot he set up for arrows. Extra strong bands. He atttached a small ball grip on arrow nock to allow holding with pinch grip. I think he took the nock off and carved the ball grip. A small nail could be inset the same way, with head providing a grip. I forget how he guided the arrow but I used to have a catalog that sold a wire arrow insert for some wood slingshots. Would be easy to make something similar.
This would be easy to carry, easy to pull out & use. Light weight, inexpensive. May not count as primitive, using rubber tubing.
I can't find the video at the moment but there is a lot on there. A Scandanavian also had a wood sling bow about 2 feet long with a rubber tube "string". Bow didn't bend, rubber pulled. That may fit in a back pack.