I would look to the signage in Tokyo for an example. The buildings have columns of signs listing the floor each one is on. Definitely not what we're used to which might hurt adoption at first, but it works for them.

In the lobby, by the elevators. Offices generally don’t rely on walk-in traffic the way that retail or food/drink do.

The biggest challenge I see is in how to segregate commercial and residential traffic. Residents will not mostly want to live somewhere that they encounter random strangers walking through their hallways all the time. A purpose-built residential tower can limit access per floor fairly easily. In low-rise buildings with living area above retail, you segregate at the door to the upper floors.