Essentially the question boils down to "How can one apply the following raw-SQL-fueled approach in EF6?" (is it even possible?):
How to determine position of row in sql result-set?
Update: This is not what I am looking for:
https://stackoverflow.com/a/1165249/863651
It doesn't employ ROW_NUMBER or something similar in db-side. It uses linq purely on the C# (aka it fetches all results and then enumerates them yikes!)