For cross platform framework. I would recommend Avalonia https://avaloniaui.net/ https://avaloniaui.net/ It has the flexibility and cleaner version of WPF but a

For cross platform framework. I would recommend Avalonia https://avaloniaui.net/ https://avaloniaui.net/ It has the flexibility and cleaner version of WPF but also lets you build it all in code if you choose like Flutter. They have a support business to support the project. So you know it will be well supported for years to come. The team is very responsive to the community also. If I was Microsoft I would just fork Flutter and add C# support and call it a day. Flutter is really flexible for mobile and desktop and has a ton of community support with libraries.