In Belgium they appealed to local nationalist feelings and anti-communist sentiments.

This can be clearly seen in the fact that there wasn’t a Belgian SS Division, but several separate organisations for the Flemish speaking part of the country and for the French speaking part (Wallonia).

A great example are the 2 SS Sturmbrigades:

5th SS Volunteer Sturmbrigade Wallonien was created as the Walloon Legion by Rex, the most prominent Walloon collaborationist party Rex in order to gain influence in the new order. They focused on anti-communist goals and claimed the unit was in accordance with Belgian nationalism.

6th SS Volunteer Sturmbrigade Langemarck was created around the same time as the Flemish Legion with similar goals by VNV, which was in a power struggle with Rex. They however focused on the Flemish nationalist story, along with the fight against communism.

What’s important here is that these formations became part of the Waffen SS, the armed wing of the “regular” SS.

We often see black and white depictions in popular media: all Wehrmacht are just soldiers (the Clean Wehrmacht Myth), all SS are sadistic monsters.

In reality, many of these men may have believed in the Nazi ideology, but really were “just” soldiers, fighting regular warfare. The foreign Waffen SS units especially were put on frontlines that would make for good propaganda. In the case of Belgian SS units: the Eastern Front, where they would fight “the bolshevik threat”.

Volunteer SS-men from occupied countries going home and talking about how they were Einsatzgruppen, committing genocides or guarding concentration camps would probably fuel anti-German sentiment and the already mounting acts of resistance groups and partisans.

As far as I know the Germans recruited for these units based on local nationalist (Wallonia), independence (Flanders) or similar feelings.

Hope this helps!