Eating definitely means swallowing. It could even mean that you save your fingernails up to make your favourite recipe, and then you eat them. Always say you "bite" your fingernails, or if you want to sound like a lazy native, just say you bite your nails.

Hi Liz! You could technically say "I eat my fingernails", but it will sound a bit weird to native English speakers. Definitely use "I bite my fingernails" instead :)

Hi Luz! In my opinion, eating something requires swallowing. So, unless you are swallowing you're fingernails, I would say "chewing". 😊