No you cannot suffocate from congestion.
When you're congested and you cannot breathe through your nose it can feel like you may be about to suffocate but even though your nasal passages are somewhat blocked they are not fully blocked and you still get some air and oxygen through your nose.
So you still are usually able to breathe at least some through your nose even though you have nasal congestion.
Also you can breathe through your mouth as well when you're congested so as long as you're able to breathe through your mouth when you're congested you will not suffocate.
To be able to suffocate you would have to have both your nose and your mouth completely blocked for at least a minute or longer and then when you cannot get air into your lungs you cannot breathe and then you suffocate.