We have pdf files uploaded in the media of wordpress and used in our website. As these pdfs are duplicate content of the original publishers, we have marked links to these pdf urls as nofollow. These pages are also disallowed in robots.txt

Now, Google Search Console has shown these pages Excluded as "Duplicate without user-selected canonical"

As it comes out we cannot use canonical tag with pdf pages so as to point to the original pdf source

If we embed a pdf viewer in our website and fetch the pdfs by passing the urls of the original publisher, would the pdfs be still read as text by google and again create duplicate content issue? Another thing, when the pdf expires and is removed, it would lead to 404 error.

If we direct our users to the third party website, then it would add up to our bounce rate.

What should be the appropriate way to handle duplicate pdfs?

Thanks