Do a little iOS dev since that has 100x more learning resources.
Once you grok iOS, you'll be at home with macOS since they follow the same patterns.
Stick with storyboards, don't bother with SwiftUI (no, really, don't do it) and try to use as much default out of the box behaviour as possible, instead of wondering 'how do I do that X thing I did on platform Y'.
Storyboards are slow compared to Live Preview, and lead beginners to adopt bad patterns like Massive View Controllers rather than composable/testable SwiftUI components. Not to mention its horrendous XML format.
Citation needed. Even on Apple silicon, I'm not even sure Live Preview can crash faster than Interface Builder and it has no shortage of practice.
> lead beginners to adopt bad patterns like Massive View Controllers rather than composable/testable SwiftUI components
There is no requirement at all on how big a storyboard is and allowing things to occupy the same *.storyboard where they would have to separate XIB files is an imporvement where it is useful.
> Not to mention its horrendous XML format
Where it does not come at other costs, standard formats (XML) are easier to operate with external tools over bespoke formats (turing complete Obj-C or Swift code). The properties in those files were more numerous than their SwiftUI counterparts, but they served a purpose.
Working with SwiftUI and the bonanza of implied default behaviors required to achieve its terseness add new salience to the idea "it is better to be explicit than implicit".
Go where the puck is going, not where it’s been. It’s obvious that Apple is heavily investing in SwiftUI to implement their vision for multiplatform app support. Did you see a single storyboard in WWDC22? 21? SwiftUI examples were ubiquitous. You can argue for Storyboards until you’re blue in the face, but they are destined for the dustbin.
Once you grok iOS, you'll be at home with macOS since they follow the same patterns.
Stick with storyboards, don't bother with SwiftUI (no, really, don't do it) and try to use as much default out of the box behaviour as possible, instead of wondering 'how do I do that X thing I did on platform Y'.