on first page load `id` will be nil, so it renders all the things, later you can broadcast out a message to subscribers something like `"conversations:123"` and update on the dynmically generated partial

example.html.tex

<div data-texas="conversations"></div>

view.ex

defmodule ViewModule do
  def conversations(_conn, id) when is_nil(id) do
    conversations_html = Database.get_conversations()
    |> Enum.reduce("", & &2 <> "<div data-texas="conversation" data-texas-id="#{&1.id}">#{&1.text}</div>")
    
    ~s|
      <div data-texas="conversations">#{conversations_html}</div>
    |
  end
  
  def conversations(_conn, id) do
    ~s|
      <div data-texas="conversation" data-texas-id="#{id}">
        Database.get_conversation(id)
      </div>
    |
  end
end