If only every service I need gave other options. In any case, the card numbers are not connected to me or the account in any publicly accessible way. Thats part of the whole point of running them off a separate phone. I dont give anyone that number except for the purpose of 2FA, so SIM swapping wont work, the sim card never leaves the house, so scan based exploits wont work, and the phone doesnt have the hardware required to be vulnerable to more sophisticated phone based attacks. If any major government intelligence agency wants in theyll find a way, but using a separate dumb phone should be significantly more secure than using the SIM in my regular phone.