My first piece of advice is do not take advice from people who don't know about snow tires, especially if their results are coming from their imagination. Unless they have a really good imagination, in which case you might be fine!

There is an entire subforum dedicated to winter biking, go there.

In the meantime, understand that your choice of words is confusing. You talk about a MTB and that you want snow tires for a fixie. Plenty of MTBs are fixies. In fact, I think a 26er fixed gear is the best all-around winter bike setup for a number of reasons which I will not go into here. And you have plenty of studded options.

It sounds like you want a 700c studded tire. The next thing you need to know is the clearance on your "fixie" - will 32cm tires fit? how about 35?

If you are starting your search for studded snow tires with the Panaracer PT I am afraid this is going to be a long journey.