Each of you mentioned ELECTRUM. Is this a program/app/utility that can be downloaded on an iPhone (to make things easier for my father)? Or can it be downloaded on a Mac (I/we only use Mac computers, no PCs/windows machines at all ever)? Or is this a PC/Windows computer mandate type thing?
There is no IOS version of electrum, but that's available for macOS and you can use it on your Mac.
You can see the list of operating systems supported by electrum on
its official website and download any of them.