Do you want to build an app using MAUI? Unless you build an app that barely deviates from the template, expect to desperately search through decade old Xamarin documentation and figure out the details through painful trial and error.
Good luck.
It is a way to get people choosing the "official" path (ie. choosing MAUI) to experience Avalonia. They are hoping you come for the MAUI and stay for the Avalonia and become an Avalonia developer.
As for, why choose the Avalonia version of MAUI, there are three reasons: - Linux support (the big one I think) - Drawn framework (same renderer on all platforms) - WASM support (probably useful sometimes but not the real draw)
They are making a big deal of WASM here because it is easy to demo. We can all go into it and run it. But do we want to use it for our apps?
As for, why not Avalonia directly? To loop back to the beginning, it is because you do not yet know Avalonia and trust it. The Avalonia team is hoping this helps with that.
MAUI is supposed to be a wrapper around native widgets. The fact that they had to use Avalonia under the covers to get it to work on Linux seems to defeat the point. (Avalonia is a complete UI toolkit, like Qt or Flutter, that owns the entire stack from XAML to pixels.)