This looks really cool! Are there any plans to open source the code so that people (I) can run it locally? I doubt the service wants me adding my 1000+ feeds.
How do you keep up with 1000+ feeds now? I feel using Gnus is quite efficient, but of the 664 feeds on Feedbase currently I'm subscribed to "only" 304.
In any case, I quite like the idea. I self-host TT-RSS, and flip back and forth between using the native web UI, and Elfeed with the TT-RSS API as a back-end.
However when I started working on Feedbase (2015) I wasn't really good enough at Haskell to accomplish the task before I giving up in frustration, so I fell back to my usual preferred scripting language, Perl, for the part that fetches the feeds and updates the database and for the nntp server - I only implemented the (quite simple) website in Haskell.
I've gotten a little better since then, so my little blog-engine, Lantern, which also uses nntp as the main "interface", is written completely in (beginner) Haskell.
One approach that I have found useful is to make sure that any stored data is in a form that is approachable from a portable standpoint, not coupled tightly to any one language. It's also helped if I want to try re-implementing some existing solution, because I have that known data as a starting point for comparing what I know with what I want to learn.
I don't neccessarily, or ever, read all of my feeds. I just quickly scan through the headlines in categories I'm currently feeling interested in. And most feeds don't update weekly or even monthly. It's kind of like how you can 'read' reddit, or HN, but not actually visit every site or read every comment thread. Except I don't depend on third parties for aggregation or moderation.