Well, lobste.rs has tags and then you can block whatever tags you choose to block, and for HN you'd need a reader that classifies / auto-tags posts and allows blocking out tags, which you'd start doing after verifying the auto-tagging classification works reliably.

Sounds like a bit like a tall order, not sure it's "just a weekend project", would (for my purposes) probably work best as a browser extension for just the listing of posts (auto-tagged and then optionally tag-filtered) to then open them in one's browser, allowing normal native reading+posting+voting+etc.