I use HN through an app, and articles use the embedded browser, which strips the chrome so reader mode isn't available. I can open the link in my regular browser (Firefox), and from that I can use reader mode, but that's a couple of extra steps.

I'm, if you're writing an article about mobile games, the website should be usable on mobile without reader mode. That shouldn't even require saying...

Firefox's Reader View doesn't fully reflow text in <pre> elements (it only wraps the individual lines to fit), so it looks bad even on desktop.