add SubscribeAsync extension method
ADD
WalletWasabi.Fluent/Extensions/ObservableExtension.cs
+using System.Reactive.Linq;
+using System.Threading.Tasks;
+
+namespace WalletWasabi.Fluent.Extensions;
+
+public static class ObservableExtension
+{
+ public static IDisposable SubscribeAsync<T>(this IObservable<T> source, Func<T, Task> onNextAsync) =>
+ source
+ .Select(x => Observable.FromAsync(() => onNextAsync(x)))
+ .Concat()
+ .Subscribe();
+}

add SubscribeAsync extension method