I don't think there is an exact equivalent.
Plugins like PictureChooser work around this by using IModalHost
from the presenter - e.g. see https://github.com/MvvmCross/MvvmCross/blob/v3.1/Plugins/Cirrious/PictureChooser/Cirrious.MvvmCross.Plugins.PictureChooser.Touch/MvxImagePickerTask.cs
Other plugins rely on static
s or globals - e.g. see https://github.com/brianchance/MvvmCross-UserInteraction/blob/master/Chance.MvvmCross.Plugins.UserInteraction.Touch/UserInteraction.cs
For your plugin, you could require that users provide a custom interface in their app (e.g. in the presenter) or you could add something to IModalHost
as a pull request.