You should manage something right now since you are thinking about what happens after you die. Have to teach your family members or have to trust someone else who knows everything about how to recover.
Exactly a must thing to do.
A true story from my experience. Years ago, in early of 2018, my friend asked me what happens if someone dies and his coin on cryptocurrency exchanges. I introduced him about crypto and he asked this question after reading news about a sudden death of a CEO of an exchange (I think you knew that case too). I told him that he should write down his email, email password, exchange account information (password, 2FA) and any related thing to his accounts.
I also told him that even his wife can get access to his phone, email but if suddenly exchanges ask for KYC before approving withdrawal request, it will become terrible case.
Unfortunately, he died in a motorbike accident a few weeks later. His wife fortunately has a notebook in which he wrote down all things but does not know what to do with it. She came to me, asked for help and all went well.
From this story, if anyone does not make backup of such things, a sudden death will be a termination of all cryptocurrency assets on exchanges or in custodial wallets too.
I managed a notebook to manage all my credentials related to cryptocurrency. So in case of death, someone should be able to handle the funds. I wrote a couple of a number of my dearest friends who are able to recover. And I am teaching my family members as well. But the notebook is under my control of me. I don't trust anyone right now.
You did a good plan B.