Should ReactiveWindow be available when using ReactiveUI with Uno/WinUI3?

Question

I am struggling with getting started with ReactiveUI in WinUI3 with Uno. I started by going through the "Compelling Example" on the ReactiveUI site but hit a roadblock: ReactiveWindow doesn't appear to be available in XAML or code-behind.

In what may be a related issue, in XAML I am unable to get anything to be recognized in the "reactiveui" space when using their suggested code:

<reactiveui:ReactiveWindow 
    x:Class="ReactiveDemo.MainWindow"
    x:TypeArguments="reactivedemo:AppViewModel"
    xmlns="http://schemas.microsoft.com/winfx/2006/xaml/presentation"
    xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
    xmlns:d="http://schemas.microsoft.com/expression/blend/2008"
    xmlns:mc="http://schemas.openxmlformats.org/markup-compatibility/2006"
    xmlns:reactivedemo="clr-namespace:ReactiveDemo"
    xmlns:reactiveui="http://reactiveui.net"

1. Is ReactiveWindow an actual thing that should be available when using Uno/WinUI3?

2. Should Visual Studio 2022 have intellisense options as I type "reactiveui:" before compiling if my XAML starts with the above?

I wish there were more examples out there, particularly on the ReactiveUI site, for using it with Uno but there isn't much information out there from my searches.

Thanks so much for your help.