I love the idea of having an ontology for everything but as you already said, AI probably is very efficient at it already so the manual work on posts without context is tedious for probably little gain.
I also have to skip most notes as none of the categories matches.
"If the stars align, nostr is going to get a nice map app 🤩" is technology -> nostr but is that a meaningful ontology? How about "motivational"? How about "community"? I think, many categories overlap and for different people different dimensions are relevant.
I think I would experiment with LLMs and ask an LLM API for the top 5 labels it can come up with for any such post and then ask the user to pick from those or pick another label.
Also please allow the first coarse categorization as labels. If I clicked on Food & Drink cause it's the right category but I don't want to dive deeper, the worst user experience is to have to click back to click skip. How about letting me assign it or skip from the submenu, too?