In addition to the three physical keyboard layouts in this post, there's a fourth one which has an extra key on both the right and the left side of the keyboard. An example is the Brazilian Portuguese layout Model M (pic: https://www.clickykeyboards.com/wp-content/uploads/2023/03/I...). The Apple test would be able to identify it, although I've never tried it in practice. I don't think the modern Brazilian Apple keyboard uses this arrangement.