Olivetti by Allie Millington

A heartfelt novel praised by Tom Hanks in the New York Times as including "a conclusion nearly impossible to divine and yet so perfect it includes that most tactile of memories..."
Being a typewriter is not as easy as it looks. Surrounded by books (notorious attention hogs) and recently replaced by a computer, Olivetti has been forgotten by the Brindle family—the family he's lived with for years. The Brindles are busy humans, apart from 12-year-old Ernest, who would rather be left alone with his collection of Oxford English Dictionaries. The least they could do was remember Olivetti once in a while, since he remembers every word they've typed on him. It's a thankless job, keeping memories alive.
Olivetti gets a rare glimpse of action from Ernest's mom, Beatrice—his used-to-be most frequent visitor—only for her to drop him off at Heartland Pawn Shop and leave him helplessly behind. When Olivetti learns Beatrice has mysteriously gone missing afterward, he believes he can help find her. He breaks the only rule of the "typewriterly code" and types back to Ernest, divulging Beatrice's memories stored inside him.
Their search takes them across San Francisco—chasing clues, maybe committing a few misdemeanors. As Olivetti spills out the past, Ernest is forced to face what he and his family have been running from, The Everything That Happened. Only by working together will they find Beatrice, belonging, and the parts of themselves they've lost.