Apple is pretty notorious for building hard to comply with arbitrary rules for their walled gardens. When it comes to the app store they won't tell you why an app was rejected even if you follow all published rules... there are other rules they just don't tell us about.
When it comes to developers Apple is a real shit-heel company.
I love onhockey because it has multiple leagues. However, on iOS devices the ads/popups are horrible to deal with (even with brave), so I'll use nhlbite.com when needed. I don't know of another site like onhockey that has all leagues.
There's also nhl66.ir that provides great quality streams, but you need a VPN to watch now. nhl66 also does not work on iOS anymore. Works fine on Android.