Yes it's possible as can be seen already, the US are planning on testing that venture.
The banks are definitely going to account for volatility
So even if your Bitcoin for example is worth 10 million Naira
The bank are going to take the value lower to account for volatility.


Besides if such option are opened for say Bitcoin, it's rate of downtrend Would reduce and uptrend would increase.

But Our country isn't anyway near there since our bank is even ban from dealing with cryptocurrency.