On the path of greater engagement of Dynamics 365 and Teams Microsoft introduced teams chat feature under sales app. Please refer below link for the announcement
Please refer below documentation for more information
How to enable the chat feature in Dynamics 365 Sales app here is the step by step documents
https://docs.microsoft.com/en-us/dynamics365/teams-integration/teams-install-app
Please refer below video for the steps to enable unfortunately I am not tenant admin so can’t enable to display list of channels in Dynamics 365 Sales app.