It would take a software engineer half an hour to write that custom software. It would take a government years to amass the political will to target such a small section of the population, and then potentially hundreds of thousands of dollars for a government contractor to offer a solution and implement it.
There's always going to be a big difference in threat level between a piece of software which already exists and a piece of software that could exist. For example, when you're snatched off the streets by the secret police, and they go to investigate what you've been doing in the country, they might be able to request from HQ a list of HTTP addresses fetched from the IP address associated with your apartment, but they're unlikely to be able to request that HQ write some software to go back retrospectively and count bytes of individual connections you made.
> (Would it help if I wrote that code right now and put it on GitHub?)
No, but it would help if you wrote a patch for APT which made it use HTTP range requests to hide the size of the files it downloads. That should only take half an hour, right?
(Would it help if I wrote that code right now and put it on GitHub?)