“Eating on the Street”
Did someone spread a blanket out on the street and have a picnic? What are you asking? If the concern is that people see you (IE the comment about sitting near the window of a restaurant), then why is sitting around the table with other people any different?
Regarding walking around and eating, even inside it may be an issue regarding brachos and bracha achrona, birchas hamazon (IE where is the kvius seuda etc…), depending how where you go from/to.