Mobile advertising delivers advertising to phones, and its interesting role next to a screen network is reaching the same person around the same place.
Run together, the two channels do different jobs. Screens establish presence in a location and reach everyone there without permission or install. Mobile ads follow up, retarget, and complete an action the screen cannot. The combination is stronger than either because the screen supplies attention and the phone supplies the transaction.
The caveat is that location-based mobile advertising rests on data whose supply is narrowing. Device identifiers have been progressively restricted, location permissions are increasingly denied by default, and much of the inventory sold as precisely geo-targeted is modelled rather than observed. Ask what the location signal actually is; the answer is often coarser than the map in the pitch.
The screen has an advantage worth naming here: it needs no identifier, no consent and no third-party data to reach the person standing in front of it. As mobile targeting gets harder, the physical channel gets comparatively stronger.