Re: It's the usual story.
> I am intrigued by your comments about interoperability
Last time I looked at it, the iPhone still "locked" the POP3 account by not issuing a QUIT command immediately after checking for messages. This used to be a real problem when checking email from multiple devices.
AFP was fine between OS9 computers but mixing Windows / Linux was... challenging.
Purely on a hardware aspect those iPhones/iPads have always had a proprietary cables and the idiotic pentalobe screws. Macbooks have proprietary M.2 SSD interfaces.