Duress passwords for mobile banking

I wish financial institutions would offer duress passwords as a security feature for online banking. Especially with the widespread use of mobile apps that allow for the transfer of funds, sadly it doesn't seem farfetched to imagine an assailant demanding that I send them money using my phone.

By using a duress password to "sign in", a user would be redirected to a sandbox environment where the user interface and notifications would look the same, but where actions would not actually be carried out. This way an assailant would believe that I had complied with their demands, but behind the scenes the account would be locked until further notice.

Security is a delicate balance between convenience and risk. Duress passwords seem like an elegant solution since they don't require adding steps to the user authentication flow, while offering meaningful protection.