To be honest, I don't know much about how credit cards can be associated with phone hardware. I would think it could conceivably be tied to phone #s. In my case the phone is unlocked and it's not an esim, which I understand we will all be moving too soon.
I wonder if it might have something to do with Google Pay or Apple Pay that ties hardware information to payments? And as for Esim, it might make it so that you can't distinguish phones based on their physical sim card so it perhaps introduces a possibility of reliance on hardware.
But this is all speculation on my part. I just don't know and I haven't made whatever precautions would be needed.