Make this bot an admin in your channel to add comment buttons to all posts.
DiscussBot
Bot info
Add this bot to your channel to get comment buttons under new posts.The buttons will open a page with comments and log you in. The bot will notify you when someone replies to your comment.See this channel for example:https://t.me/DiscussThisThis bot was created to demonstrate Telegram’s new seamless authorization for websites. If you are a developer, see the details here:https://core.telegram.org/bots/api#loginurl
Bot commands
/start
/help