@Tom C I didn't spot anything in Apple's macOS or iOS announcements that looks like it will cause major headaches for developers using Xojo to build macOS or iOS apps.
According to this Article (in German) :
App Notarization is now required
While one can do this manually with own CodeSigning Scripts or 3rd party tools... a decent IDE should have these features built-in.
So that's going to be a "ToDo" for Xojo to make our lives easier.
zsh is the default Shell
Better check your Shell Scripts. Or make sure they are explicitly using the Shell you know is working with your commands.
And on the second Page of the Article (in German) :
This is the beginning of the End of Objective-C
The new Combine Framework is only available for Swift. No more Objective-C support.
So in the mid/long term we probably want/need a way to use Declares working with Swift. Or the "Xojo Interops (to come)" work with Swift, too.
And (being pessimistic)... in the long term Xojo probably needs to add a new Build Target: "macOS (Swift)" to somewhen replace "macOS (Cocoa)". So they better start preparing - who knows if that might be the case in 2-3 years. And I'm sure it'll take quite some time to move the XojoFramework to Swift.