I wouldn’t feel comfortable picking up ammo this way. Too risky. Ammo might have corrosive primers, could be squib loads or could be tampered with.
I have brought a lot pre-owned ammo.
Never had a problem.
If in doubt with hand loads I just break them down for components.
Corrosive primers so what just remember to clean your firearm. I have shot thousands of rounds of them.
I am glad others are afraid leaves more for me.