Its been two years since you were last asked for this, and you said when it gets traction. 

Well, its getting traction, v11 is coming out, there is ever increasing list of public projects, https://avaloniaui.net/Showcase, plus countless WPF inhouse migrations like the ones we do. Serious money is already being involved, there are already many teams who would rather pay you for controls than waste their own cycles repeatedly making functionality. 
WPF is indeed dying, .net foundation is treating it like a leprous uncle, Avalonia is literally getting more love from some foundation projects than WPF does, some wpf libraries are still targeting net5 with no intention to update them. MS wants you to migrate away from it to MAUI (after failing to get us to migrate to UWP) and it lacks cross platform support which neither of MS replacements like MAUI offer, and MS has a big influence over what they do. Chances of that succeeding are very slim, as big as they were for UWP. Even barring the lack of Linux support, WPF has this pre-mortem smell that Silverlight had, people stick to WPF becuase there really is no roadmap that will retain full functionality.

Chicken and the egg debate is losing its appeal, we are presently even willing to sacrifice some functionality to get away from WPF before it sinks. 

The writing is on the wall, there is a clear and present need for quality commercial 3rd party controls for Avalonia, from the paying customers. I understand there is work to port the styling in WPF controls and to remove any windows P/I dependencies you might have. But whoever of you largest control makers steps on the market first and opens the flood gates, will get the first revenue and a foot in the porting of larger WPF projects, and certainly the inertia going forward.  I am posting this to each of you. 



Time to wake up. "Wake up and smell the ashes" :)