a person (as a store employee) who assists shoppers to choose their purchases or who personally selects merchandise to fill telephone or written orders
Personal shoppers are specialised assistants who select merchandise and perform shopping activities for other individuals or businesses to save time and effort.
Not sure if there has been a recent publication on it. You might want to frame the concept within the current “co-creation” and “Service Dominant Logic (SD logic)” literature: co-creating, communicating and delivering value.