[Asura]

Well, this won't give you an entire site download but if you want to download a specific page as a PDF, you can use Firefox on Android. I use it all the time.

How to do it would be that you go to the page you want, click on that three dot thing on the upper right corner in Firefox, click on page then save as PDF. To open the PDF, use an app called WPS Office. It's free and even open Microsoft Office documents as well.