Favor I was able to get the import to work. It was my bad as I changed the name of the file in the location it was saved to; not in iTunes File Sharing.
I have a couple of things though that I noticed need to be fixed with this. First, objects are imported with a texture of 50% smoothness, even if that was not what they had. So, the smoothness and metallic sliders need to be fixed in importing. Also, you should be able to add models to Polydust from the Apple Share Sheet. In other words, if you had a model you downloaded from the internet, you would see the model in the Files app on iPad, click the share button, and find an option that says either, "Open in Polydust" or "Copy to Polydust." This is necessary because not everyone is going to have a Mac and be able to access iTunes File Sharing, making it impractical to copy assets into Polydust in this manner.
Thanks Aexus for the suggestion; however, I have way too many files in my Polydust app to be able to navigate and find the correct one to copy and paste.