I've never heard about mouth to nose for humans either, so that seems to have been a very local course.
I do have fairly recently learned that if there is no pulse and you are alone, it is ok to forego the mouth to mouth as long as you do heart compressions. The heart palpitations are so much more important and as long as you keep compressing the chest then there will also be a slight exchange of air. (So you still have to check that nothing is stuck in the throat first).
If you are two and help is going to arrive soon then mouth to mouth can be added, or if you are more than two (so you can take turns).