Yes you can put Vicks VapoRub under your nose and it will help with congestion and help you breathe when you have a stuffy nose or other congestion.
Whenever I have a cold or stuffy nose I will put some Vicks VapoRub under my nose which helps open up my nasal passages and allows me to breathe better.
I add the Vicks VapoRub under my nose both during the day and at night and I breathe and sleep better when I have it under my nose.
Just don't get the Vicks VapoRub in your eye as it can burn your cornea but putting it on your chest or under your nose is just fine.
You can also use a Vicks Humidifier with some Vicks on it to help with congestion and the Vicks VapoRub will be put into the air to help you breathe.