If one account for all currencies & cryptocurrencies will be compromised then all will disappear from that account. Correct me if I am not right.
We use a special banking solution from Thales security. Private keys from cryptocurrency accounts are stored in hardware, and the solution is the inability to copy these keys, even with full access to the device. You get full access to your cryptocurrency accounts, without worrying about the safety of their storage, the creation of keys cold wallets and other complexities associated with the blockchain and the cryptosphere. Those. on your part this is a normal bank account.
We use safe guard accounts for fiat. we have a small payment institution license from the Czech bank, we actually provide full (except for loans and deposits) banking services and related guarantees.