Android Binary https://github.com/barteksc/PdfiumAndroid
Windows Binary https://github.com/bblanchon/pdfium-binaries
Low Entry HTTP Request https://www.unrealengine.com/marketplace/en-US/product/low-entry-http-request
There is a template widget in plugin's content folder but it has HTML GET Request nodes from Low Entry. If you need to view online pdf files, you need to use an HTML plugin with ByteArray support. If you have another one or you use only local PDFs, just delete that nodes.
Even if you don't want to view online PDF files, you need to attach an empty array to ByteArray pin of Read PDF function. You can use "Make Array" node.
Relaese has an APK for ASTC arm64-v8 to test it.
Plugin is for Unreal Engine 5.1 and up. Windows and Android platforms supported. This is runtime plugin. It don't work in editor.
You need to use it in a C++ project. After first compile, you can copy it to a blueprint only project.