The situation
Accounts do not inherit.
When someone dies, their photographs, documents and holdings do not pass on the way a house does. What passes on is whatever the people left behind can actually open.
Provider processes exist, and they are slow, uneven and sometimes impossible. Two-factor codes point at a phone that has been cancelled. Recovery e-mails live inside the account that is locked.
A card changes the shape of the problem. Instead of negotiating with companies, the person you chose holds an object, and separately, the one thing that opens it.
One approach
Split the object from the key.
This is a common arrangement, not advice about your particular circumstances. Talk to whoever handles your affairs.
I
Write the vault
Put the small set of things that matter on a card: master passwords, recovery phrases, where the important documents are.
II
Place the card
One card stays with you, one at home, one with a lawyer, a bank box or the person who will need it.
III
Place the password
Never in the same envelope as the card. A sealed letter, a second trusted person, or instructions that only make sense to family.
IV
Say it out loud
Tell the person a card exists and what it is for. An unexplained card in a drawer is the same problem again.
Being findable
is part of being safe.