How to monitor data volume transfered from server to client

I wonder if there is a way to have matomo tracking the quantity of data received by the browser after the page was fully loaded.
(And I wonder if this is a bad idea to do that with matomo)

The goal is to have an idea to what quantity of data our website is generating for the network and the final user.

I guess it would be possible using custom variables, but may be there is other ways.
Anyone have any suggestions for me ?