Many https://github.com/cheeaun/awesome-hacker-news

this one is even more recent https://news.facts.dev/

The latest I think is https://app.hn-reader.com/ (25 days ago https://news.ycombinator.com/item?id=40443995)

Here’s one I’m developing for iOS if you want push notifications or summaries of linked articles

https://apps.apple.com/ie/app/hazumi-news/id1670237209

Why would it need one? Genuinely interested in the need, not being facetious.

We have, actually! It’s called “web browser” and there is a high chance you already have it on your device.

What would this app do?

I like octal

I mean a mobile app for Android and Apple

Go to the app store of your choice and search for 'hacker news'.