Is there any possible way on how I could pass a complex data type, specifically a DataTable from one project to another using interaction.xml? the only valid data types that it accepts are String, Number, Boolean, and Date.
Use the JsonUtils component to serialize your datatable to a json string. You can store the json string in the GlobalDictionary. When you other project is ready to receive the datatable, it can deserialize the GlobalDictionary value back into a datatable.
This method can be used to store most complex types into the GlobalDictionary.