<PackageReference Include="System.Reactive" Version="6.0.0" />

System.Reactive.Linq.ObservableImpl.AutoConnect<T>

sealed class AutoConnect<T> : IObservable<T>
Automatically connect the upstream IConnectableObservable once the specified number of IObservers have subscribed to this IObservable.
namespace System.Reactive.Linq.ObservableImpl { }