Molly chews sticks and twigs all the time when she's out. We have tons of trees all over in our yard and in the neighbourhood so there's no avoiding them. The squirrels break off little branches and thrown them around so we can't rake them all up all the time.
She grabs sticks and twigs and goes to town. I don't think she swallows the bits she chews off but I can't tell. I try to substitute a toy but she runs around grabbing more twigs and bits of bark. Am I worrying for nothing? Should I let her chew sticks?
Not unless you want splinters in her gums & cheeks, a stick wedged in the bridge of her mouth, a sharp stick stuck in her intestinal tract, etc... being realistic, not dramatic btw
"Leave it" and "drop it" will become popular phrases for you.
You can -- perhaps when she is a bit older -- teach her to just carry the stick like when you are on a walk. I have done that with Diesel, he knows once he starts trying to chew it gets taken away so he just walks with it, proudly in his mouth!