I wrote a post about my experience using it for a year if you're curious: https://getglyph.app/blog/3-building-glyph-a-year-with-swift...

I didn't speak to developing for macOS specifically. The tldr is that it's not quite production-ready but it's easy to mix SwiftUI with UIKit so you can adopt it incrementally. I really like Apple's vision for SwiftUI and they're catching up with missing features very quickly.