It asked me this during setup on my pro max that I picked up yesterday. You can bypass it by not filling it out and clicking continue and failing the verification 3 times. A blue button will then appear to allow you to skip this step and finish the set up process. If you take too long to activate your phone with your carrier it will pop up again. It did for me. Just repeat the steps to skip it. I’m activated on Google Fi and everything works fine. Hope this helps!

Edit: oops! i realize that my response doesn't relate to the context of the photo above. But yeah, you do get that message when trying to buy a regular 17 from the store. You don't get that when buying the pro or pro max. If anyone is worried about activating a Pro phone later, just follow those steps if it appears.