Gazebo can validate integration logic, launch structure, navigation behaviour, sensor assumptions, and controller wiring. It cannot automatically validate wheel slip, lighting variation, sensor noise, network behaviour, mechanical tolerances, or human interaction in the physical environment.
What simulation can support
For the retail robot, the implemented stack supports mapping and navigation, shelf-level detection and tracking, inventory persistence, ERP updates, and customer-guided navigation in a simulated store.
That is meaningful system work. It should still be described as simulation.
What remains unclaimed
Detection accuracy, navigation success rate, inventory precision, physical latency and deployment reliability all need measurements from a physical environment. I do not have those, so I do not quote figures for them.
Clear qualification does not weaken the project. It shows where the next engineering phase begins.