App did not transfer from old iPhone to new iPhone, any way to side-load?
So, I finally broke down and purchased a new iPhone XR to replace my aging iPhone 6. The update/restore data process went better than expected, with just one app, a PDF Reader from KDAN Mobile, not able to download - it shows up on the home screen as a greyed out icon, and nothing happens when I tap on it. KDAN makes an updated version of this app, but it has a hefty subscription price; I'd rather just use the old version with its limitations.
First of all, would this be a trivial matter for iMazing to suck the old application out of my old phone, and put it into the new phone? I'm guessing the answer to that would probably be yes; are there any implications to doing that? Such as, having done that kind of operation can I still go back to using iTunes to back up the phone and transfer files into and out of it?
Secondly, I have a lot of snapshots of my data going back years (yay, ZFS!), and it's possible that I have a copy of the .ipa file for this application, either in the directory that iTunes used to use for storing applications, or in the Trash. What I'm less confident about is whether I have the latest .ipa file ever released; if the app has been pulled from the app store there is probably no way to upgrade it to the last one released, is there? What would be the process for getting an app onto the phone, assuming I can find the .ipa file in an old backup?
Thanks for your input.