Well, this seems pretty useful. Certainly worked well when I tested it on the Web Tiger Team site.
However, I do wonder whether the RSS feed aspect might be limiting here. I mean, how often do people manually generate an RSS feed on a static website?
I'd say the answer is 'pretty much never'. They're annoying to create/edit by hand or with a static site builder, and hence they're usually quite rare on the types of websites this tool was made for.
So while I think the widget works well when used properly, I feel like the vast majority of static sites won't be able to use it simply because they don't have an RSS feed.
It should be very easy to automate RSS feed generation with any consistently laid out static site (even if it's hand written).
If you're using a SSG (I presume most are), there's things like jekyll-feed[0]