I'm fairly new to DSC and I'm trying to apply VSS storage size settings within my configuration. Is it possible to gather data from the node that is being configured with a WMI query and run that through a foreach loop? Or would I need to put this into a DSC script resource?
You would be best off building a custom resource – they're easier to debug and maintain than a Script resource. But yes, that's what you'd need to do – the MOF can't contain any executable code apart from a Script resource.