The reason code name was "Oslo" is that the team was based on Oslo, Norway.
Likely that is related to Microsoft acquisition of "Fast Search"
That technology is used in Bing and SharePoint...
Introducing Delve (codename Oslo) and the Office Graph | Office Blogs:
"the newest member of the Office 365 family: Delve (formerly codename Oslo). We announced it and the Office Graph last week at the SharePoint Conference keynote. You can get a closer look at Delve by watching this Garage Series for Office 365 episode"
GUI resembles Pinterest...
Introducing Delve (codename Oslo) and the Office Graph | Office Blogs
Microsoft also announced that Codename Oslo, an upcoming Office 365 product previewed this year, will be officially branded "Delve." The company says Delve will use machine learning to become familiar with a user's needs and routines, which it will use to deliver real-time insights.
There is a completely unrelated app in Microsoft store with the same name