There's an android app called FitzyTV. It USED to be in the google play store and amazon app store, so it was legit (legal?) for a while. Now only available as an apk, while the lawyers hash things out. It's sort of a clearing house app for all the channels tht are online that your regular cable subscription is SUPPOSED to give you access to.
Anyhoo, I log in with a Fios acct registered in NJ, and I get the two Boston sports channels, as well as a bunch of other RSNs. I'm assuming logging in with your New England based Xfinity acct would give you the same channels.
There are NO popup ads or anything like that, and I've never had an issue with virus or malware. It appears to be a clean app, as it's former availability in the two app stores would imply.