I wasn't aware you can use extensions on mobile Chrome... Anyway, I use an app for HN on mobile. Much nicer experience. (Materialistic is the client du jour)
To my knowledge, you can't. You can use many, if not most, Firefox addons on mobile (I use ublock on FF mobile, which is nice). This extension is for Firefox.
I'm not really sure if Firefox addons/extensions work well in iOS. I can imagine a few reasons it might be more limited, but I don't have an iPhone to test.