From last month's .net 5.0 preview 8. hopefully someone contacted Microsoft lol. Or that it'll be ready in preview 9. I might have to make a twitter to keep track on the progress on this. It says .net 5.0 is supposed to be released in November but who knows. Oh nevermind, just took a look at their roadmap. Arm64 support for WPF isn't expected until the first half of next year...so yeah hopefully someone from serif is in contact with the dotnet team at Microsoft.
https://github.com/dotnet/wpf/blob/master/roadmap.md
