I've made a bit of progress -- actually installing UNITY from the Visual Studio Installer.

I can open the Unity folder in the samples, but then don't know how to run the application. How do I run a sample under Unity?

It is a pure C# application. I know nothing about engines, so I want that to be as simple as possible. I just want a standard C# WPF application to be able to run on Linux and MacOS.

I did download the SDK; just want proper guidance to see the right sample that I can model and duplicate.

I'm exploring the option of creating cross-platform application and understand that NoesisGUI provides cross-platform support compatible with WPF. (There's also AvaloniaUI but it's an unstable beta) In practice, I can't figure out how to get started with it. I'm looking at their tutorial samples and...