@mariani1@felyashono Yes, legacy Windows app continue to run on Windows in tablet mode.
The way Win11 deals with the overlapping-windows issue is to offer snap-to modes everywhere. Snapping windows to tile or have them appear full-screen is very easy using drag gestures, and works well for tablets.
Porting UIKit to AppKit is not necessary, thanks to Catalyst (which I worked on). You can literally run iOS apps right out of the app store on a Mac desktop.