Can the SwiftUI document architecture Take a file as read-only; never to be written out Take files too large for memory (multi-MB, or even GB) I wouldn't want the system to read a gigabyte size file into memory by default. If the system can use a memory-mapped Data as the representation, that'll be something I can make do. It would be even better if I could tell the system that I'll handle all the reading, all I need from it is a reference to the file's location on disk.

Instead of a .sdef file (or older formats) made in advance and stored in an app’s bundle, I wonder if the script dictionary can be set soon after the app opens? I seen related API, with a note that the scripting file reader ultimately calls that API. I grok about 90% of that API, but I’m not sure it’s possible.

One of the features of Big Sur and ARM-based Macs is that they can run iOS and iPadOS apps. The iOS app format is used for iPhones and iPods Touch. This format is reused for iPadOS apps. But isn't the format used, for the third time, for tvOS apps? I've read descriptions of iPhone/iPad/AppleTV triple-platform apps. So, can AS-Macs run tvOS-only apps too? If not, why? Wouldn't they be easier, since they're designed with taking a non-direct-touchscreen in mind?

In the original SwiftUI, you still used NSWindow and friends, so the older techniques would work. But with SwiftUI 2 taking over all of the command reception and handling, where is printing supposed to be recognized (and the PDF or whatever gets sent back)?