Sec,ch,ua,mobile:,?0 Now

: It follows the Structured Field Values format, using a question mark followed by a boolean: ?0 : Desktop (False). ?1 : Mobile (True).

For more technical implementation details, you can refer to the official documentation on MDN Web Docs. Sec-CH-UA-Mobile header - HTTP - MDN Web Docs

: Include interactive elements that rely on mouse-hover actions, which don't exist on touchscreens.