I bought a used iPad 2, mainly for reading. After a short while I found out that it won't run a more recent iOS than 9.3.5 and that there are basically no apps that run on this iOS version (rendering the iPad 2 almost unuseable--I really couldn't believe it). I have been able to open PDFs with the iBooks app that came with it, but I don't like the way you have to swipe from right to left on the screen to get to the next page. Is there either a way to switch to a "scrolling" behaviour in iBooks, where you can just swipe up and down on the screen to move seamlessly between pages, or a PDF viewer app that supports this and can still be installed on iOS 9.3.5?
This may be a solution - please give feedback so I can correct.
Login with the same appleid on a more modern apple device (iphone etc) or possibly on a desktop computer.
Purchase (for zero dollars) the apps "USB disk" with the purple logo and "Adobe Acrobat".
On the ipad 2, open App Store and either look at "Purchased Apps" or browse to find the identical apps you already "bought", and download them.
The option to download an older version should appear.
The abovementioned apps have a version that works under 9.3.5 on ipad 2, open .pdf and use vertical scrolling. I just checked!
I also recommend you get the Chrome browser at the same time as some websites will work with it when Safari will not, and its availability may be terminated...