Hey, i tried using Avalonia with LibVLCSharp. Same problem as WPF... The underlying issue is the rendering. Take a look at the 3rd Party controls using Avalonia (for example CefGlue) they use Images for rendering.
For full and easy support there is a method needed to get the output buffer in some raw format. Basically the same way capturing in DirectX works.
Ok, using that workaround (see Github) the Avalonia UI can load the Wpf-UserControl itself.
This would be the windows way. But the class can be changed to set the handle by platform, and using the airspace fix just for windows.
I cannot say, if Avalonia Controls can be added to the airspace fix
Question is, does airspace issue happens, if there are no overlaying controls? Maybe it's even easier to do, without support for overlaying controls on windows