How can you find a list of your registered firearms in Canada?

As a private citizen, you can't.

What locality? In the U.S. there is no federal registration, and only a few states require any type of registration. The basic answer is, you can't, because it doesn't exist.

If you're in a country which has registration, such listings are typically not made available to private citizens.

Law enforcement only.

The basic answer is, you can't. In the United States, there is no list. U.S. federal law does not require registration and only a few states require it.