On the official side, these leagues have apps that stream the games and the Red Zone channel (NFL). They are subscription-based ie require payment.
No endorsement implied but there are many sites that deliver streams of sporting events. From a phone/tablet perspective, however, most of these streams are unusable because they rely on Flash.
I won’t post sites or links here except to say that Reddit has subreddits dedicated to sports streams and will identify those compatible with iOS devices.
TY