Win32 and WinUI serve different purposes, they aren’t meant to replace one another. Win32 is simple but also really low level. It’s great to get a window handler and handle low level events but building a modern graphical UI requires at minimum a layout system, that’s where WinUI comes handy.

Also you can now mix Win32 with WinUI via the concept of XAML island. It’s not perfect but you don’t have to be blocked in one world or the other.

Though I personally prefer dealing with WPF via AvaloniaUI, styling with winUI is often too frustrating…

https://www.avaloniaui.net/