if "Bitcoin is a cryptocurrency" As they say, why some people are pen drive "Physical currency"?

The real question is, as they say, “Bitcoin is a cryptocurrency,” why do some people not consider “pen drives” (the physical device that stores public and private keys and manages coins on the blockchain) as “physical currency”?

For example, let’s say Bob gives Alice a pen drive containing one bitcoin. Alice trades her favorite programming book called “JavaScript” for one bitcoin included in her pen drive.

how?

Alice(book) -> Bob (pendrive)
Bob(pendrive) -> Alice (book)

Is this considered a valid transaction (Pendrive->Book) despite not being on the blockchain? In this hypothetical scenario, were there any valid transactions even if nothing was done directly on the blockchain?