The Belgians who managed to escape in 1940 were, like the Dutch, small in number and by 1944 made up a 2,000 strong Brigade under Major Jean Piron and 5 SAS (Belgian Independent Parachute Company). There was an RAF unit of 1,200 men with Royal Belgian Navy personnel manning two Flower Class corvettes, K.226 HMS Godetio and K.193 HMS Buttercup. Some 38,000 Belgians also served for the Germans on the Eastern Front in the 27th and 28th Waffen-SS Freiwilligen Divisions "Langemarck" and "Wallonien".
The Belgians also had a Brigade from the Belgian Congo that did garrison duty for the British in the Middle East. After the Allies went through the country several Light Infantry Battalions were raised, but I can't say if they did more than Line of Communication duties. People sometimes are unaware that the Belgian King allowed the SS to recruit his subjects.