So I built p-Hacker, which uses a ML pipeline to cluster the HN corpus into distinct topics and spot current trends beyond simple keyword frequencies (though it does that, too). You can search for full topics or simple keywords, and compare them side-by-side.
I started off running it on my laptop just to work out the mechanics, but after lots of iteration thought maybe I should put it online publicly. There's lots of room for improvement (the data only goes back about two years, nightly updates take a couple of hours, item topic membership could be improved).
Feedback welcome.
[1] https://news.ycombinator.com/item?id=22233457 [2] https://hntrends.net/