I was using the Samsung Notes app to write on PDFs in the Galaxy Tab S6 Lite device. Unfortunately, when you click on the icon to add PDF to the application, it doesn't have any option to search for a specific PDF file and there is no such option to navigate trough folders in the device. Those features are a MUST, because when you have a big quantity of PDFs on your device, it's impossible to find what you want. Worse yet, they list the PDFs in alphabetical order, which makes it even worse because It doesn't show recently added PDFs files.
I couldn't even believe that the app didn't have this feature and I searched online and I found this in an official Samsung page:
However, in the video explaining how to import PDF, there is an option to navigate trough folders in the device, however in my device there is no such option (I have the newest version of the application).