Postgres foreign data wrappers allow you to create a table from a CSV file
without actually loading the CSV file into Postgres.
You can then query the data in Postgres but not update it.
Updates you make to the CSV file are immediately seen in Postgres.
Given this file . . .
You can use csvsql to generate your CREATE TABLE statement for you.
Then just tweak it a bit to create your foreign table.
Now you can query the table.