Not sure about SIM cards but you can still use cash to buy prepaid phones along with an amount of minutes/text to activate. Like the kind of prepaid phones that you you see the vendors sell x minutes/text/data. e.g. I’ve never been asked for a credit card to buy a Tracfone. Some places like Best Buy will ask you for other information to sell it but none of it needs to be real (ironically Best Buy asks for a phone number to buy a prepaid phone, LOL). You do need to set up a Tracfone account online to actually activate a phone + plan, not sure about the other prepaid vendors.

Store them offline. A simple USB stick with screenshots of your QR codes & backup codes would cover this.

Some people also print them out to keep offline but you’d need a printer handy to do that.

TBH I’ve never understood why someone would store backup/recovery codes in the same application they store their passwords in. If your password storage is compromised then you’d indeed be completely and utterly compromised when the attacker also has your backup/recovery codes.

See the other post https://lemmy.dbzer0.com/post/312389