This is a good point, especially with a lot of 2FA being tied to phone numbers.
My dad set me up as his legacy contact for his Apple account, and he uses their Passwords app. But I’ll need to remember to keep his phone (and the bill paid) until I can be sure the 2FA won’t be needed for something.
While I’m sure presenting a death certificate to a bank would be enough to trigger processes that won’t need it, I’m betting having that access would make many things easier.