BS, Apple most definitely is encouraging their developers to make separate iPhone apps and separate iPad apps, clearly you are not a developer. Apple even boast and brags that they now have over 500,000 iPad apps. iPad apps do NOT work on iPhones because of the huge discrepancy betweeen the small iPhone screens and the much larger iPad screen layouts, and aspect ratios.
Lets use one developer that made separate iPhone apps, and separate iPad apps for example. Like Adobe Lightroom which has both app versions. Now lets pretend that Apple makes a foldable device that is both an iPhone and a iPad mini, which would be similar to Samsung's Galaxy Z Fold 3 foldable device. Now which iOS version do you install on Apples foldable device? Now which app version would you install on this Apple foldable? Would you install the Lightroom iPad app version, or the iPhone app version? Try and remember that there is two separate app versions of the same app. Clearly you can't install both app versions on the one physical device. So if you install the iPhone app version, then that version would work for both the iPhone display, and the iPad display. Developers would still have to modify their app for app continuity when a user folds and unfolds this device. Plus if there is an iPad app version, it couldn't be used on the smaller iPhone display. Not to mention you still have the app continuity problem when a user folds and unfolds this device.
Mark my words you will NEVER see a foldable from Apple that will be both an iPhone and a iPad mini in one physical foldable device. I will bet big money on it, and I can take that all the way to the bank.
Ultimately the 500,000 apps created by Apple developers, and companies would now have to take every piece of code from their iPad apps, and then place that code in their iPhone app code versions. They would still have the app continuity probllem to contend with as well. Google and there Android don't have that app separation problem, because Google from day one encouraged their developers to create one physical app that supports both smartphones and tablets. Now Android and its developers still have app continuity issues when users fold and unfold these foldable devices. But nothing like the impossible problem that Apple created when they went out of their way to get their developers to create separate app versions. Especially when Apple and its developers are facing all the problems with foldables, like the 2 in 1 foldable devices (Galaxy Z Fold 3). If you can't see the major roads block that Apple is facing with foldables, then you need to actually become a developer, or at least talk to some other intelligent developers.