Livebook, which is an elixir code notebook built with LiveView includes collaborative editing with presence, so it absolutely can be used in that domain. LiveView is built on phoenix channels, so it's all bidirectional communication. The client can send events from JavaScript. We use js hooks for the pings in LiveBeats for example:

    //js
    Hooks.Ping = {
      mounted(){
        this.handleEvent("pong", () => {
          let rtt = Date.now() - this.nowMs
          this.el.innerText = `ping: ${rtt}ms`
          this.timer = setTimeout(() => this.ping(rtt), 1000)
        })
        this.ping(null)
      },
      destroyed(){ clearTimeout(this.timer) },
      ping(rtt){
        this.nowMs = Date.now()
        this.pushEvent("ping", {rtt: rtt})
      }
    }

    //liveview
    defp handle_event("ping", %{"rtt" => rtt}, socket) do
      {:halt,
       socket
       |> rate_limited_ping_broadcast(socket.assigns.current_user, rtt)
       |> push_event("pong", %{})}
    end

Check out livebook.dev, it's pretty mindblowing! It's like Jupyter but for Elixir, and fully collaborative. It's about as close to Google Docs as I've seen.