How do you decide if it's work-related reading/browsing or not? So watching a music video on YouTube is clear but I'd say HackerNews is muddy, leaning towards entertainment. For example you need to sleep to work too, but that doesn't count. HN may provide general nourishment about latest tech news and have interested articles that elevate your general knowledge but hard for me to pin that down as hours worked. That's the problem with work today, it's not easily measurable, in the old fashioned way of thinking of work as putting caps on bottles I'm guessing most people do far less than they believe, I wouldn't be shocked if it was only a couple of hours for many.
Yea well you have to dig through a lot of trash to find the gems. But since it is part of the deal you need to take the time into account that you need to wander through the mud.
Officially I won't count the hours that I use for this at home. But at least for me that is definitely work related.
If you're not taking notes on it so you can access and use it later, it's likely just an idle interest. Reading's not the same as learning. Also if you would read it without getting paid, it's probably not work.