Almost everything on SwiftUI 2 is about iOS and almost everything on macOS menu bar apps is on older SwiftUI.

I have a menu bar app which I started two years ago, when SwiftUI was new. I now want to redo it using modern SwirtUI.

Is there any information on creating a basic menu bar app with a single popup using SwiftUI 2? Everything I’ve seen so far is a sort of hybrid.

Unfortunately SwiftUI do not embed menu bar. You have to use old NS code and App delegate. You can take a look at this project. Look in applicationDidFinishLaunching in AppDelegate file

https://github.com/Sebastien-Remy/HackingWithmacOS-10-TimeBuddy

Hope it can help you