The Xfinity Channel is listed as Beta, but you can get it from the Channel Store. https://channelstore.roku.com/details/123132/xfinity-tv-beta
Here the announcement: https://blog.roku.com/blog/2017/01/31/xfinity-tv-app-for-select-roku-devices-begins-beta-trial
and here's the FAQ: https://customer.xfinity.com/help-and-support/xfinity-apps/xfinity-tv-app-on-roku-faqs
I'll post my initial review as soon as I get home and can try it. :)