I recognize that slack side conversation are not be able to use on trigger now.
I expect to be added slack side conversations as a trigger action same like ticket or mail side conversations.
I know that posting slack message as trigger action is possible, but this method cannot remain the record on ticket.
If someone know a method can achieve my request, please share it.
Thank you for reaching out.
You may use the Push Notification from Zendesk to Slack, more detais can also be seen on this post here: https://support.zendesk.com/hc/en-us/community/posts/4409515187866-Push-notifications-from-Zendesk-to-Slack
I hope this helps, but please do let me know if you may have further queries.
Kind regards,