What are your opinions about Avalonia? It runs on Windows, Mac, Linux, Android, iOS and WebAssembly, with the mobile platforms being in a more immature state as support was added recently.
MAUI is the continuation of Xamarin.Forms, while Avalonia is the spiritual successor to WPF, albeit open-source and cross-platform. MAUI uses platform-native controls (which means the same control may appear or behave differently between operating systems), while Avalonia builds everything with Skia, so it renders the same in every platform. I think of it as the .NET alternative to Flutter, though with a more desktop-centric focus, instead of being mobile-first.
I have not used it yet but it seems the most promising .NET UI framework and I’m hoping to build a personal project in the following months. The first Release Candidate of Avalonia UI v11, which stabilises the API, was released two weeks ago.
Also, they have created Avalonia XPF, which uses Avalonia UI as an abstraction, in order to run (Windows-only) WPF applications on MacOS and Linux.
While the core Avalonia framework is and will be free to use (without price tiers that limit functionalities) XPF is targeted mostly towards businesses and there is a Pro version (they are planning to build a business in order to fund core Avalonia developers).