Pass ReactiveObject ViewModel between Android Activity in Xamarin

Question

I use ReactiveObject as a ViewModel in Xamarin.PCL:

public class PlanViewerViewModel : ReactiveObject

Inside the ViewModel, there are a lot of ReactiveUI logic such as:

FilterIssueTypeCommand = ReactiveCommand.Create<string, List<IGrouping<int, StandardIssueTypeTable>>>(
                searchTerm => 
                {
                    Func<StandardIssueTypeTable, bool> filterIssueType = d =>
                        string.IsNullOrEmpty(this.IssueTypeSearchQuery) ? true :
                        Contains(d.Title, this.IssueTypeSearchQuery) ||
                        Contains(d.Category.Title, this.IssueTypeSearchQuery) ||
                        Contains(d.Issues.Count().ToString(), this.IssueTypeSearchQuery);

                    return RealmConnection.All<StandardIssueTypeTable>().Where(filterIssueType)
                                          .GroupBy(g => g.CategoryId)
                                          .ToList();
                }
            );

this.WhenAnyValue(x => x.IssueTypeSearchQuery)
    .Throttle(TimeSpan.FromMilliseconds(500), RxApp.MainThreadScheduler)
    .Select(x => x?.Trim())
    .DistinctUntilChanged()
    .InvokeCommand(FilterIssueTypeCommand);

_groupedStandardIssueType = FilterIssueTypeCommand.ToProperty(this, x => x.GroupedStandardIssueType, new List<IGrouping<int, StandardIssueTypeTable>>());

In Xamarin.iOS development, I could easily pass the ViewModel between each controller using this code:

var finderController = segue.DestinationViewController as PVFinderTabBarController;
finderController.ViewModel = this.ViewModel;

I am wondering how could I do it in Xamarin.Android?

I know there are several ways to pass data between Activity:

• Pass it as a string, int, bool: This is what I am currently use
• Serialize the object into JSON: slow
• Implement Parcelable or Serializable: I don't want to use it because that means I need to copy my ViewModel into Xamarin.Android project.

If I do it that way, there is no point in using ReactiveUI.

I am thinking of using Application class in Android and create one instance of my ViewModel in it so every Activity could refer to that. Something like this:

[Application]
public class GlobalState: Application
{
    public PlanViewerViewModel viewModel { get; set; }
}

Is there any other solution?