This is a good a question and the core of your problem is that the exports try to do different things on a dashboard:
Image, PDF, PowerPoint - These export types try to give you only what you are currently seeing. In the case of your data table, they will indeed only export the current view.
Excel - Gives all of the underlying data, regardless of view
Now there’s the kicker; if you want a large multi-page PDF export, use a report / scorecard.
Reports are designed for long form exports and if you create a report that has the same data as your data table, you can use the pdf export there to allow for a multi-page export of all the data.
Here’s a doc that will help you if you’ve never seen reports before.
https://www.dundas.com/support/learning/documentation/create-view-content/report-basics-and-concepts