Zero liability does not apply to peer-to-peer services, such as Zelle or Venmo if you authorized the payments. For example, if you purchase an item using Zelle and you never received the item, this will not be covered—even if it was a scam and payments were made from a Navy Federal account or through the digital banking app.
If someone steals your account credentials and makes a transaction without your consent, Navy Federal will provide protection.
Gift cards are not covered regardless of where purchased. They work the same as cash.