I listen to XM radio on the internet I do not get NFL or any Sirius only channels on the internet. They may have merged but the are not the same.
What they have done is taken certain Sirius Channels and mixed them in with XM channels. I'll give you a good example. "Classic Vinyl." Sorry, I don't remember what channel that is off the top of my head is a Sirius channel. The XM version of that Channel was called "Top Hits." It's no longer there. Also there was Big Rock on XM for the 80's, now it's "Classic Rewind" yet another Sirius channel. and Big Rock is gone. On the other hand "60's on 6" from XM stayed, replacing whatever Sirius had as an equivalent. Channels like Deep Tracks are also available on both XM and Sirius with no additional charges. If you have a Sirius radio Deep Tracks is in a different location then on an XM radio.
So there are Sirius channels that are mixed into the XM subscription. Just not stuff like Howard and the likes.