Bring our own channel without using Direct Line

Following this document https://docs.microsoft.com/en-us/dynamics365/omnichannel/developer/how-to/bring-your-own-channel, we must integrate with Direct Line to bring our own channel into omnichannel. With a platform with hundred thousands or millions of messages, this is a costly solution. Please support a solution where we can bring our own channel and handle it ourselves without using Direct Line. Thanks!