If you had dual citizenship (e.g. Canadian + US), do you even need to tell a bank about your US citizenship when opening an account?
Can't you just open it as if you were a Canadian only? Even your US SSN wouldn't be associated with it, so for all the US G and the bank know you're just someone with the same name and birthday.
As a random aside: The US Gov is practically the only country in the world who tries to collect income tax from US citizens living abroad. The fact that Americans who move away have to file US tax returns for the remainder of their life is bonkers.