port in number to existing Xfinity Mobile account/line

Can one port in a number to an existing Xfinity Mobile By-the-Gig account/line and thereby "replace" the current number on that Xfinity Mobile line?

Say I sign up for the "free" Google Pixel 7 deal (bill credits for 24 months) and port in a number (NUMBER1).

Then at some later time, I may want to port in another number (NUMBER2) and use that instead of NUMBER1.

Can one do that? Will the bill credits for the "free" Google Pixel 7 phone still continue?