In the past, I have researched many cellphone plans, as I decided to switch from a Verizon plan. Xfinity Mobile was a plan that I researched, since I have Xfinity for home internet.
For phone service, they are considered an MVNO, which means Mobile Virtual Network Operator. This means they do not own the networks they use (Verizon) and are network managed when on a busy tower. It also means they do not have access to the shared towers that are not owned by Verizon. This may or may not mean anything to you, but something you should consider. You might think you are never gonna be in a place that has lots of people banging on a tower, but think about being stuck in a traffic jam and everyone using their phones. In this case, you might not have adequate service to even make a phone call, much less use you data.
I am providing a link to a website that does extensive research on all of the cellphone plans. They are independent and do a great job. It might get a little technical, at times, but you'll get the jest of each plan you might be considering.
You searched for xfinity - Mobile Internet Resource Center
I have an RV and travel pretty extensively. We use the internet for everything. When traveling, we use upwards of 100GB's per month. Our coach is connected to the internet 24/7 for tracking, streaming music and TV, as well as supplemental navigation. So, our needs are data related; not so much phone calls. We do text extensively.
For our needs, we settled on AT&T for 3 lines. In addition, we have one line with visible (Visible.com) which is a Verizon MVNO and truly unlimited "high Speed" internet data for $25/month. Visible has the same restriction as Xfinity with respect to towers and network management.
Feel free to PM me if you would like more information on any of this....