I suspect that countries like El Salvador might accept Bitcoin for such proof. How is the situation in your own country? My country will not accept Bitcoin because the government is anti-crypto.
This is only possible in countries like El Salvador.
If I go to a bank or passport office in my country to show bitcoins as proof of funds, my only destination will be jail.
Even though my country ranks 35th in the world in terms of Bitcoin usage, Bitcoin is strictly prohibited in my country.
So my country's banks and government have put in place strict laws to control the use of Bitcoin. So we can never show Bitcoin as proof fund in bank or passport office as collateral for visa processing.