Wolfhooks can be found under trees near Wolvendom. Sometimes they are hidden in bushes. Use sword unit to cut bushes out.
You can get 20 or more Wolfhook here.
You can purchase Wolfhooks from Botanist Chloris. The refreshes every 3 days and the items don't change. You can't see her at night.
Genshin Talents (Skills) Guide
All Mondstadt Luxurious Chests and Shrines Locations
The Exile
Farming Fireflies (Luminescent Spine)