Mobile integration is a deliberate handoff between a screen in the space and the phone in the visitor's pocket. Usually the screen starts something the phone finishes: a QR code that carries a basket to checkout, a display that sends a menu to the table, a video that continues on a device the viewer already trusts with their details.
The direction matters. Screens are good at attracting attention in a place and bad at capture: nobody types an email address on a wall. Phones are the opposite. Moving a visitor across at the right moment is the point; the screen earns attention, the phone earns the conversion.
The caveat is that every handoff loses people, so it has to be worth the step. A QR code that opens a page the visitor could have found by searching your name is friction with no payoff. The handoffs that hold are the ones carrying context the phone could not get alone: this store, this table, this product, this moment in the video.
Also design for the phone that scans and then walks away. The single most common failure is a landing page assuming the visitor is still standing in front of the screen, when they are usually already in the car park.