Hi @Kalyana Chakravarthy Darshanam ,
I can't speak specifically towards an Activity Feeds Management out-of-the-box service but there several Azure services that you can leverage to build your projects.
Azure SignalR Service is a service that allows real-time communication for your application over web sockets. The service is a robust platform that does scaling efficiently and easily, but you can always elect to host SignalR inside your app yourself but it isn't as robust.
Azure Web PubSub is similar to SignalR service but the model is more aligned to publisher subscriber.
Azure Service Bus is a messaging platform that allows a client to receive messages on a particular topic that have been queued by a sender. This messaging model is a sender push client pull model so when your client is ready to receive the messages, it will pull it off the queue. This can be coupled with Azure Function to have serverless compute easily pull messages off the topic the function is subscribed to.
Hope this helps.