Pixel 4 BYOD incompatible?

My wife bought a new pixel 4 from google only a few months ago.  We were fine using metroPCS as our carrier, but ever since we moved into our new home Metro has been trash. Dropping calls, texts not sending, and sometimes no signal at all. 

We were happy to switch over to XM.  I called today trying to switch our phones over.  My Pixel (1) XL has no trouble. My wifes Pixel 4 was incompatible. Even though Xfinity sells the exact phone in their store.  I don't understand how this works.

Also felt kind of insulted when customer service suggested that I buy a new Pixel 4 and add $22 a month to the bill to pay for it... when I have the exact phone sitting in front of me.

Is there anyway to make a BYOD Pixel 4 work on your network?