Microsoft Teams has a limitation that we can’t schedule a meeting in a private teams channel
You might try to hack by trying to convert a private team to public and then schedule a meeting, that’s not possible also
However, it’s possible that you start a meeting and send invite interested audience by sending them a link to the meeting
1.Start a meeting by clicking on the video icon (6th icon ) below chatbox and select ‘Meet Now’
2. This will start the meeting, next step is to copy the invite link by clicking the link icon visible like in below image and sending across the link to an interested audience, or we can even call them into the meeting by searching them in the search bar
However, yet again it’s not much helpful if the person to be invited is not part of that private channel, external person’s will not be able to chat as evident from below video
However, whatever chat the host puts or the members of that private channel put, that will be visible in the channel
Thank you, let me know your comments and views!