Xfinity Mobile (Verizon service) question

I know this isn't an Xfinity sub but I believe Verizon owns the towers Xfinity uses, I know this is a long shot but Xfinity is an official subreddit and I'm not comfortable asking questions there.

To start, I am currently on Xfinity mobile and I'm wanting to switch to Mint Mobile. The problem is I'm four months behind on payment. I've already researched and from what I found I believe I can't port my number to a new carrier until my balance is paid in full. My question is, can I use my phone that I was using on Xfinity if I have Mint Mobile give me a new phone number or will I still have issues because of the past due balance?

My other question is how is Mint Mobile's service and where are you located if in the United States (roughly of course). I'm in the metro Detroit area, downriver.