So, I know Holland and Belgium have their own scenario competition but what about other countries? Perhaps some people here can share if there are competitions just for scenario players in their country and if there are, what the set up/format is?

There are quite a few Scenario event in the U.S. that happen. Most are points and objective based usually running 2 teams but I have heard of some running 3. One of the biggest events is Supergames that happens twice a year. Hope this helps you.