Basically i have set up my 1x1 RG within the Pop Up where im searching for a specific Datatype. I pass that Data to the Reusable Dropdown element and the RG within the Dropdown has the Reusable Dropdown Property of the 1x1 RG.
The only difference i see with your approach is that you load Data into the custom state of the Pop Up when the Pop up is visible, right?