I don't know if this has been mentioned before, but this is something we recently implemented.

We have a Slack channel where all new tickets are funneled to give visibility to our team on incoming tickets, but there are a lot of people who wanted to be able to give an internal note on a ticket even though they were not an agent in Zendesk.

We hooked up our trigger to easily create a Side Conversation in Slack in less than 5 minutes and now other people in our organization can chime in on a ticket from Slack. Were able to do this all in one channel because we are a smaller org, but it would be fairly simple to add some additional routing to segment the tickets into channels based on context. Here is the quick and easy setup:

1. Create an HTTP Target (Admin > Settings > Extensions) using this URL: /api/v2/tickets/{{ticket.id}}/side_conversations.json

2. Method: POST, Content type: JSON, and use basic authentication. 

3. Create a trigger using this target. Here is the basic JSON to use:

{
  "message": {
    "subject": "{{ticket.title}}",
    "body": "*{{ticket.requester.name}}* from *{{ticket.organization.name}}* submitted a new ticket (*{{ticket.id}}*)\n *Ticket Description:* \n {{ticket.description}} \n *Ticket URL:* https://{{ticket.url}}",
    "to": [
      { "slack_workspace_id": "ENTER_ID_HERE",
        "slack_channel_id": "ENTER_ID_HERE"
       }
    ]
  }
}

This is the easiest way to find your slack workspace and channel IDs.

There is a lot more you can do using this endpoint. Documentation here.

There are probably better solutions that take someone to code a solution, but for orgs like mine where we are short on resources for these type of integrations this was an easy solution that has given us a lot of value.