<PackageReference Include="System.Reactive" Version="6.0.1" />

System.Reactive.Subjects.IConnectableObservable<T>

public interface IConnectableObservable<T> : IObservable<T>
Represents an observable wrapper that can be connected and disconnected from its underlying observable sequence.
namespace System.Reactive.Subjects { public interface IConnectableObservable<[System.Runtime.CompilerServices.Nullable(2)] out T> : IObservable<T> { IDisposable Connect(); } }