We acknowledge the customer demand for Private Channels and have been hard at work on it. Private Channels is currently in preview with a select group of customers. We expect to release the feature to the public later this Fall, and will update here when we are starting to roll out to all customers. We appreciate all the feedback you have provided to us on this forum and thank you for your patience.
Try this instead is not an option. Absence of private channels is a huge barrier for using Teams in our unit. Project teams would be quite unhappy that anyone in the organisation can have access to their chat at any time. Creating a team for each project is not an option either, as with short-term projects our SharePoint space will turn into complete mess quite quickly.
Beside, all alternatives products allow private channels.