I know that it is possible to secure a deposit in the bank with any type of asset, but with the possibility of permanent disposal of it, meaning that its owner cannot ask the bank to lock it.
What I would like to ask is whether this product exists in the banking system of your country and why, in your opinion, are there central banks that do not allow it? Also, is this possible on online virtual banks?
Product or services like this one might not be attractive anymore. The world is full of uncertainties that even when you plan there are always unforeseen occurrences. One might assume that anyone who subscribed to this package should have emergency funds that will serve as backup but sometimes these funds are not enough. So you expect someone with health problems to die because of a lack of finances while they have money locked up in a bank or post office. Savings are for the living and not the dead. We all know that it is important to save but there should be an avenue for people to access these funds in times of emergencies. This is why banks provide services like fixed deposits and other savings plans.
I don't think any bank offers such a service except it could be a personal or special agreement with the local bank. I don't know if the central bank of my country approves such service but I think it it might affect the monetary policy of the country especially if it is in foreign currencies like the dollar. I would never advise anyone to engage online virtual banks for these services. Most of these online banks are not under the supervision of the central banks and they can easily scam customers.