Just because every potion in the two textbooks Harry looked at involved magical ingredients doesn’t mean all potions require a magical ingredient. As I read it, Harry found the potion he used in a more obscure book suggested by Prof. McGonnagal or Flitwick, probably something like a wilderness survival guide. Converting acorns into a beacon would be pretty helpful for getting found by search parties.
Just because every potion in the two textbooks Harry looked at involved magical ingredients doesn’t mean all potions require a magical ingredient. As I read it, Harry found the potion he used in a more obscure book suggested by Prof. McGonnagal or Flitwick, probably something like a wilderness survival guide. Converting acorns into a beacon would be pretty helpful for getting found by search parties.