Burner Bitcoin features nearly identical hardware to the Ethereum variant -- a secure element chip with NFC capabilities in colorful/translucent plastic -- however, we made the decision to split the Bitcoin and Ethereum versions into two products rather than creating a single monolithic wallet. This is because we're seeing that both end users and business customers want to use Burner as a tool to give specific assets rather than gifting a universal hardware wallet.
In order to generate transactions on Bitcoin, Burner directly signs transactions using it's internal private key. You can add entropy that is hashed alongside entropy from Burner's RNG during the generation process of this key, but the private is never revealed in plaintext. We will also indicate through the interface whether or not a key has been used to sign a message or not, a helpful indicator so you can be confident funds have never been withdrawn from a gifted Burner.
Like the original Burner, we offer open libraries to interface with the wallet so you can sign transactions and messages fully offline if you want to use it for cold storage rather than as a “cash like” wallet. Our long term vision is to make buying small amounts of various cryptocurrencies for those who are crypto curious as easy as buying a restaurant or retailer gift card.