I'm skeptical here, given how closely the US and Canada work together, both US and Canadian banks share an incredible amount of info with each other and not solely because of cross-border commerce. There is also a non-trivial number of US citizens living and working in Canada so there are services available to them given their special tax requirements.
In the 3 banks I've worked with in Canada, all were completely unable to access my American credit history.
The governments do share tax data, but AFAIK the banks have no way to link "John Smith SSN:123-45-6789" to "John Smith SIN:098-76-54321". They even have my US SSN number since Canadian banks report to the IRS.
Edit: here's experian explaining it: https://www.experian.com/blogs/ask-experian/u-s-credit-histo...