There is a microflow in Excel import module called as IVK_importdata you need to copy is into your module and customize it by adding you custom logic in a microflow and call it via Call microflow activity in this microflow (i.e; IVK_importdata).
Then test it.
You can use the Reference to Import Object for this. Indeed you will need to tweak or customize the logic and the context (Campaign page) where you start the import, and the imported records can be linked to that (if the target entity of you import file is associated to the campaign entity n-1)
Hope this helps