Can i use PDFTron android library for PPT and Doc files?
Yes, the latest versions of PDFNet support viewing and annotating DOCX, DOC, and PPTX files. This is dependency free (completely internal), and is available on iOS, Android, macOS, Windows, Windows Mobile, and even fully client side in the browser (pure javascript).
In particular for Android, please see our showcase Xodo application, which is completely free. It uses the latest version of PDFNet, and you can open DOCX, DOC and PPTX files.
https://www.xodo.com/
Note that XLSX support is being rolled out and will soon be available on all platforms also.