First, I think you’re not used enough to NNW ;-). The way I (and I reckon most of NNW users) use the app is to first read all items in the main window, sometimes selecting an interesting post by double-clicking its title or simply typing Enter (in “combined view” it then opens it as a tab in the background, so you can continue parsing items and later browse your selected tabs in their full glory in what is essentially Safari embedded in NNW).

Then, on many “prolific” feeds I read, I sometimes double-click on the feed title in the feeds list to open their home page (effectively marking all unread items as read in that feed).

Lastly, (same as above) I sometimes go directly to the site and read what’s on the home page, for those sites that publish their entire posts and not just an excerpt. I would click on a particular permalink only if I want to read the comments and/or react. In this case, you would not have any indication of what I’ve effectly read since I don’t necessarily have to (need to, want to…) click on each post URL to read it.

Nice idea, but unpractical as it seems…