How to force Contacts to respect "File as" (or "NickName") field for sorting and display?
As of 2019, Google contacts respect the "file as" option. 
If you have contacts named as "FirstName LastName" and use "fileasname", the display name will be "fileasname". Also, you can search even by "FirstName" or "Lastname" or any of the entries made in google contacts. (Yeah even notes are searchable).