Currently, there is partial -- and not particularly robust -- support for importing JavaDoc documentation into an Assembly.xml documentation file by way of mdoc:

https://github.com/xamarin/xamarin-android/blob/7dab4ee432dcd1e51c52dfe579023fccaf09c471/src/Xamarin.Android.Build.Tasks/Xamarin.Android.Bindings.targets#L345-L383

(This very well may have bit-rotten…)

The above support requires the mdoc utility, but we're not sure of the long term distribution mechanics of mdoc: dotnet/runtime#35852

As an alternate take, once PR #623 is merged, we might be able to instead do the conversion within generator, such that the generated code itself contains C# code comments converted from JavaDoc. This would allow us to use the "normal" csc /doc toolchain, and remove the need for mdoc entirely. (Except for updating https://github.com/xamarin/android-api-docs, but that's a separate concern.)