<PackageReference Include="System.Reactive" Version="6.0.2" />

System.Reactive.Concurrency.SchedulerOperation

public sealed class SchedulerOperation
Represents an awaitable scheduler operation. Awaiting the object causes the continuation to be posted back to the originating scheduler's work queue.
namespace System.Reactive.Concurrency { public sealed class SchedulerOperation { public SchedulerOperation ConfigureAwait(bool continueOnCapturedContext); public SchedulerOperationAwaiter GetAwaiter(); } }