I got around that by just making another google account specifically for my old cell number turned voice number. I really wanted a 505 area code but knew I'd inevitably miss a site for which I'd need to update the 2FA number, so I just grabbed <my phone number>@gmail.com and ported the number.

It's also been helpful given how many people absolutely refuse to stop calling my old number despite explicitly telling the resistant ones "I have a new number, I _will_ stop checking the old one, and I can't answer calls to it anyway".