My first thoughts would that they would appease the germans, join the allies, join the comitern, or have their own faction.

A fascist route for the Netherlands could be to restore old glory. Take lands from Belgium, rebuild a good navy, dominate colonies and trade and more stuff like that.

Historically the Dutch, even after losing their mainland, maintained most of their navy. Most notably their merchant navy which helped deliver goods around the allies. Perhaps adding a bonus to somehow make convoys for the Dutch cheaper would be nice. You can decide if this should be Democratic only thing or if it should be allowed for Communist and Fascist regimes.

Adding some Focii to help fortify the Dutch's colonies would be nice. Perhaps even allowing a somewhat ahistorical focii to allow Dutch industry to be moved to their colonies?

Having a Focii to jumpstart a quick defense against the Germans would be nice as the Dutch were very ill-prepared for the German invasion. Adding some forts, decreasing training time, and such would help with a Dutch defense.

A Fascist Netherlands would likely be focused on aquiring the rest of the low countries. Boosting its navy to alleviate naval pressure in the northern seas for the Axis would be nice as well.

A Communist Netherlands would be very tricky considering the Fascist and Democratic powerhouses surrounding you. Not sure what I can give for this one. Maybe just an early joining of the Comintern to deter early German aggression.

The Dutch also have a predominant presence in the Indoneasian region so colony development their is not unheard of neither, also in africa, for the belgians Nationalist route whould be to take back Wallonia and all, Free state congo and such

^^ Just general ideas